My son hates being on his stomach ! I try to do tummy time but when I do he just screams and puts his head down on the blanket . He will lift for a couple seconds but then puts it right back down . He will be 4 months in 1 more week and I read a article that he should be able to lift his self up really good now and he can't . I don't know what to do . I want to make sure he progresses like he is supposed to but i don't know what to do .