This is a reach but does something happen at 2 every morning to wake him up? Like a newspaper delivery and the neighbors dogs bark.
I also think it's possible that it might help to provide some soft "white" noise that lasts all night.
And tht he's having difficulty adjusting to all the changes tho it would seem that he would have in 4 months. Perhaps a regular sleeping routine, or a different one, if you have one already but it isn't working.
And it'a also possible that you go in to him too soon. He has to learn how to soothe himself back to sleep. A sippy cup of water left in their crib when they went to bed helped my grandchildren go back to sleep.
Their are different techniques to handle changing this behavior. Have you read about any of them. They range from letting him cry it out to going in, standing by the crib or sitting in a chair and wait until he goes back to sleep, to going in for just a few minutes and gradually increase the amount of time that you let elapse before going in. Pick one and try only that one for a couple of weeks and see if it works for both you and your baby.
Does he have a lovey? something soft and cuddly.
The good news is that eventually he'll sleep thru the night.