Baby bettas are tougher to care for as they’re more fragile than adults. They do need an additional feeding each day so 2-3 feedings per day. Lethargic behavior and loss of color is a sign of stress. Make sure your water is heated to the proper temperature and that the water is within all recommended parameters for a betta. The pooping seems normal based on what you described.

A pea would not be overkill if he’s actually suffering from constipation and bloating.

I would do another round of fasting for 2-3 days to help ease the digestive tract. You can also try freeze-dried daphnia as they can aid with constipation. Some bettas are picky with peas. You could try soaking the pea for a minute or two in some garlic juice if you wanted to continue that route.

White stringy poop is normally a sign of internal parasites. This is possible if you bought a sick fish. Stringy poop on its own, without a white color, is a sign of constipation usually from overfeeding or feeding low quality food. It can also happen from only feeding freeze-dried foods. Daphnia can help with constipation issues, and so can fasting for a few days.

It has white poop stuck on it and since I just bought it I didn’t observe it that much until I came home. I don’t know if the fish cant defecate or it just did and it doesn’t came out fully. I am willing to learn how to properly care for it since this is my first time. I have read the white poop thingy on your post but I still do not know what to do about it. I really do appreciate if you would help me a little bit. Thank You so much!