Baby's distyrbed sleep at nights. Help!

Hello! My baby is 8 months old, for the last 10 days he is having a disturbed sleep, he is getting in middle of nights and crying, when put into breastfeed he is fine but rejecting bottle feed, ee are having difficult times as am a working mother and cannot sleep the whole night as baby is not going to anyone else other than me! What to do plz help! He used to sleep fine but for last 10 days this is happening, otherwise whole day he is active only during night times he is getting up from 2 am then again on 3 then on 4 or 5 and from 6;30 onwards he is sleeping sound sleep again, i cannot udnerstnad what is giing on. As i mentioned only during night other time he is active. How to resolve this plz help