Have you started solids yet? 5 months you might be able to give some prune puree or prune juice. Applesauce might also do it. And fyi as you start solids, be careful about bananas if you are worried about constipation. At 10 months bananas were all my older kid would eat almost and he ended up constipated and miserable. Once on solids: prunes pears peaches are easy to remember.
Also rhubarb! That's great when in season
We just went through the same thing my pediatrician recommend a suppository for him since it had been 5 days… we first tried some prune juice. I would reach out to your pediatrician 😊
I do warm bathes! Usually for about 10-15 mins. My daughter also uses that brand.