HELP! 3 month Sleep Regression?!

We switched our 14 week old baby from her bassinet to the bassinet level of a pack n play last week because she started rolling over a lot and the PnP is wider with full mesh sides. She is now rolling onto her tummy constantly so once she rolls we let her stay there. Consequently she is not sleeping well at all anymore. Does anyone have advice/ideas on how to help her sleep better so mommy & daddy can get some rest?! I'm not sure if her sleep problems are because she's on her tummy or because the PnP is bigger, not quite as soft as her old bassinet, etc. 

Please help! Before this she was sleeping through the night.