I think it is HUGE that you prepare your child for every new experience. Talk about what is going to happen and cover things that might happen. Ask her how she thinks she will feel and how she will react to each situation. Once she tells you how she will react, give praise if it is proper or guide her on how it would be better for her to act.
Parents have a big job. It is too prepare our little people to grow into big people. Fostering unrealistic expectations will only make things harder for her in her future. It sounds like you were prepared with a toy after the 2nd day. However, did you explain to her before you dropped her off that she would NOT receive another prize at the end, but someone else would. She had experienced getting a prize at the end, did not understand that things would not end in the same manner (which is how your preparing her would have helped).
You could have even told her that MOMMY was going to have a special surprise for her at the end. Tell her you are so proud that she is such a big girl now and you had special plans afterward; however, she should enjoy her time at VBS, because that is important too.
It is also important that our children do not learn to take things for granted. Going out to eat should be a treat, going to VBS is a treat, going to the store and taking the time to look over the toys and still not get anything is still a treat because this is a great opportunity to learn wish lists.
It is important to remember, that you have to be cautious that you don't overdo the splurging. Children cannot be rewarded everyday for every action. I want to reiterate that she needs to be prepared that the VBS IS the reward. She gets to be with new friends, do crafts, and learn.
Another point that I feel strongly about, we NEED to teach our children to be good winners and good losers. No one likes an "in your face" person when they win (normal excitement - yes, ridiculous rubbing another person's nose into it - no). No one likes a poor loser, you child kinda ruined the big moment for the prize winner that day.
Teach your child some games (at 5 she can do things like Candyland, Chutes and Ladders, Memory, Old Maid, Go Fish, and MUCH MORE. These are fantastic ways to spend time with your child and helps stimulate their intellect. You be a gracious winner when you win (do NOT allow your child to win all the time!) and a gracious loser when you lose. Your reaction will determine her reactions.
One final thought, I worry that your child will grow up to feel as if she is a failure, no matter how well she does. She has to be prepared that she will NOT always get A+ grades, be the leader, be the teacher's helper for the day, be first in line, be the one that everyone wants to play with, and tons of situations that she will experience.
It is how she handles these things will determine who she is and who she will become. You do not want to set her up to feel as if she has failed, is a failure or she might eventually have such a great melt down that she just doesn't feel as if life is worth living. It is POSSIBLE, because kids (more so once they become pre-teens with the hormones bouncing around in their little body) have a very high suicide rate. I do not wish to alarm you, but I do want you to realize what a great impact this could be for her, regardless of the true importance that we put onto the situation (cut and dried - she didn't win a prize, but looking from her side - she failed her craft, didn't think her item was good enough, her self-esteem fell into the toilet and she felt punished).
Much of the early preparation will help her to know how to behave in certain situations. The more information you practice - I am serious, really practice each scenario - the better she can adjust and adapt. She'll eventually will have covered enough situations that she can think more appropriately on how she should react, even when it is has not been previously covered.
I guess I am just saying to help strengthen her skills on reactions.
I know that some parents are very much against TV; however, I think appropriate shows are needed for children to see how others deal with situations. I really liked the majority of shows on Nick, some of the kid programs on PBS, but VERY few shows on the Cartoon Network. I would watch many of the shows with my children. During Rugrats I would ask my girls if they thought that Angelica was behaving nicely, what would they have done, did they think her parents were helping her to become a good girl, and many things like that. They grew up realizing that the way that Angelica acted (bossy and mean) was NOT appropriate and would NOT be tolerated. Many shows are based around a life lesson theme. Children don't always pick that out for themselves but can learn to model/mimic either the good or bad influences of what they see. Our goal is to point them into the right direction.
Please don't misunderstand. I do not think you are a bad parent or that you have a bad kid. I don't mean to imply criticism. I hope you understand I was just trying to give you some informational tools that might help your child for all of her future interactions.
I am not addressing the psychologist/psychiatrist angle, although I do agree that children do not need medication, but better direction. However, I am not a specialist and do not presume to tell you something that is beyond my scope of education/knowledge.
Best of luck to you, and I hope that what I said makes sense.