I agree that you should see the doctor to rule out medical reason. The ear infection thing sure sounds likely. If it's not an ear infection, or something else medical, then it's time to become baby detective.
First, rule out gas. The way I used to do this is to flex my son's knees to his chest, to help him pass any gas that might be causing him trouble. Works most of the time. I even found it to be far more effective that the gas drops you can give babies.
I'm assuming you would know if the problem is constipation. So I'll bypass that part. But it might be reflux. The way that this is best handled is to elevated the head of the crib a few inches, to help keep acid down in the stomach. This is a method that my son's doctor recommended.
Also, it might just be she's having trouble learning to get back to sleep when she wakes in the night. I'm not sure how you feel about pacifiers, but it might help to keep on in the crib where she might be able to find it to put in her mouth. Also, a softly playing radio can help. Some people even say that it should be tuned to static. The low anount of noise can help soothe a baby that wakes in the night. She might even find a nightlight soothing. That way she can see that she's safe in her own room if she wakes up. As for the crying when you lay her down already asleep, the best method is to try to lay her down still awake, but very sleepy. Another helpful thing would be to hold a recieving blanket next to her body while you cuddle her. Then when you go to lay her down, spread out the recieving blanket first. Some kids wake back up when they feel the cold sheet under them.
Hope one of these ideas helps. Just remember, this too shall pass.