He only eats when the peas are held in the fingers, even though I made him fast for almost a day belly still the same.
Sorry to hear that, Gold-Fisher - has he had several days of actually eating peas, cut or nipped into betta bite-sized pieces? They do have a laxative effect.
Does he have a problem getting down to pick up food from the bottom when it falls?
Have you tried the epsom salts, mixed up with water in a container and added to his tank?
You should be able to get them off the shelf from any drug store, they're not expensive, and they do encourage the absorption of moisture and pooping in Bettas.
This is important and time is of the essence as he'll be building up toxins, from retained wastes and opportunistic internally dwelling organisms which propagate under such circumstances..
If peas and epsom salts don't work, there may may something more than simple constipation going on.
Have you found any poop, or noticed him going? When was the last time?
Any white, stringy poop at any time?
I don't remember for sure from your previous posts, but I believe your betta does have a heater, doesn't he?
This has been going on for some time - make certain you get epsom salts and hand-feed him eye-sized bits of peas if necessary.
Is there anything unusual in his behaviour or appearance, particularly any recent changes?
What about that spot he had - did it look like ich, was it white?
Is it still there, or does he have have more, or show any sign of itching, flicking, skin irritation?
Because you need to get the constipation cleared up and any ich the instant any such problems manifest, because either can kill him and fish suffer pain, misery, and illness just as we do.
But they're helpless and they need us to act promptly and in their best interests.
Just as we'd hope for prompt help if we were sick, helpless - and utterly dependent, as are they.
Almost forgot - what about that swelling he had behind his head?
Does he still have that?
If so, could we get some details?
Hang in there, you'll make him better.