Baby all of sudden sleeping on tummy! Help!!πŸ˜–

So my daughter is 4 months old. She has always HATED tummy time. Slept perfect on her back and sometimes side. Now at night when I check on her she is either sleeping on her tummy or awake and lifting her head multiple times a night. It’s weird because she has never liked being on her belly and now all of a sudden she is sleeping like this and I am terrified of SIDS. What should I do??