!!!!!HELP!!!!!! Baby won't sleep.

I have a 4 month old who has been sleeping through the night up until the last week. He is constantly waking up. He will sleep for about 3 hours then he wakes up every hour on the hour. He can't seem to relax he's rolling all over the place and isn't able to get comfy in his crib! What can I do? Am I hitting the 4 month regression? If so what do I do to make this better?