Help NO SLEEP!

My 7 week old refuses to sleep on his back. I have tried everything. We swaddle him which he hates and manages to break out of. He will fall asleep nursing, I make sure he is good and asleep and put him in his crib, 5 minutes later he's screaming. Finally last night I took him out on the couch, nursed him and he fell asleep on my chest. I said screw it and stayed on the couch thinking I would sleep a few minutes and attempt the crib again. Well I woke up 4 1/2 hours later and my baby was still out cold. He wants to sleep on his tummy. It's the only way he's comfortable. What can I do?