My 5month old is exclusively breastfeed and hasn't had a bowl movement in 36 hrs. how can i help him go to the bathroom if he's constipated?

Bowel movement: It is usually individualized and habitual in most cases. 36 hours of no movement should not be a cause for concern. At this age, stage one baby foods containing fruits/veggies can be introduced and would help child move bowel

Wait? Observe: Exclusively breast fed older babies often will skip days of having BM's. They absorb most of the breast milk. If he is not fussy, then watch for a day or two more Some times drinking 2 oz of water can help if there is fussiness My guess is you will have a stored up BM to clean very soon