Doing different things will cause worse sleeping. Getting him up when he isn't sick or obviously having a problem also causes worse sleeping.
I have three boys and all three slept through the night by 6 weeks. My youngest is now two, and while getting him to go to sleep is still occasionally a battle, once he is out, he goes all night. Here is what has worked for me.
Get your child ready for bed. Even when they are tiny, give them warning. "You will be going to bed in XXX minutes." Then make sure they are fed, etc., and put them to bed. Have a routine...you either rock, or sing, or read a story book...but have a routine. Then plop them into bed. If they wake in the night, do not go in their room for 15 minutes. (20 when they are older then yours.) Your son needs to learn how to wake up and then put himself back to sleep. Right now he is clinging on the hope that you will come and get him up (that hope will make him cry longer) and he is also clinging onto the hope that you will come and help him put himself to sleep. He wants you to do all the work.
So don't go in for 15 minutes. Because you've been getting him up, he will probably have a stronger will then that. So go in his room, reassure him, DO NOT PICK HIM UP, rub his back and talk soothingly to him until he stops screaming. (If he is whimpering only at the end of your 15 minutes, don't go in...he is almost done and back asleep.)
The first three nights will be the hardest. He still has hope. He will cry a lot and you will feel like you are being a terrible mom. But you aren't. You are training him that he can do it himself. You know the trainers on the Biggest Loser who scream at their fat folks until they force themselves to get through their mental barrier and actually run? Then they are so proud of themselves because they did it. You are working with the mental issue of training and will. And by going in every 15 minutes to reassure your son (but not pick him up or give him hope) you are able to reassure yourself that (a) he is okay, (b) he isn't soaked/dirty and (c)he isn't sick.
After a while he will figure it out and start to wake up, cry a bit, and then go back to sleep. So expect one hard week but hang tough. This really does work. Really, really, really. If you are completely consistent for a week then you will see a difference in his sleep patterns.
VickiS