hello Dr my 3 and half month old baby used to fall on her tummy on her own since her 100 th day...but since since two days she is just playing lying on her back... it seems she is not coming on her tummy...now she is 116 days old.....from the 100 th day for two weeks she always used to fall on her tummy on her own but i don't know what has happened since 2 days....she had easily crossed the first milestone but now she has forgotten.