why does my 7 week old do this?

I'm going crazy! My son will not sleep. I will lay him down and he will sleep 5 minutes and then wakes up. I get him back to sleep and it's the same thing all over again. When I sleep next to him he stays asleep but when I leave the room no he dosnt like that. What can I do? Also he has really bad congestion but it only happens in the morning. I try everything to relieve it but nothing works. Idk if both are connected but he sleeps really good at night. Just wakes up to feed and goes back to sleep.