Update: He's now using both fins to swim again and he's responsive, but he's still really lethargic (hanging out at the top of the tank and not moving a lot). The bulge is not any smaller either and I still don't see any poop - white or otherwise.
I got the Maracyn I and II and started him on that - unfortunately I was stupid and didn't think to change the water to get rid of the General Cure beforehand. He seems to have improved somewhat rather than declined though, so maybe it wasn't a mistake that will kill him.
I'll continue to dose him with the Maracyn I and II and epsom salt and hope that helps him.
Update: I've been medicating him per the directions on the boxes (API General Cure and Maracyn I and II) and using epsom salt.
All weekend he's been very lethargic and stays up near the filter, but still moves around well when he does move - both fins are still working. The bloating is still about the same and the white plug looking thing near where the poop comes out seems to be more prominent. I asked my fiance how he looks this morning and he said he saw a white sore on his side that may be leaking pus. What could that be? I should have pictures of that a little later.
He won't eat - tried a bit of a pea and daphnia for the constipation. Usually he's a very good eater, but he almost ran away from both of them.
How often should I change the water? He's in a filtered 5g tank, but the General Cure said to remove the carbon, so I've done that. His last treatment was yesterday though and the instructions on the box say to change some of the water after 48 hours. I just don't want the water quality to make him worse.
After I put the General Cure in he started moving the other fin again, but other than that I can't really tell that any of the medication, epsom salt or daphnia has done anything for his bloating. It might have gone down a LITTLE, but barely enough to be noticeable.
For comparison, the first two pics attached are from when I first noticed the bloating and the last one was taken last night (sorry for the awful quality - he won't hold still and my cell phone camera is crappy). I'll post the ones of the white spot that my fiance mentioned when I get them.
I want to do everything I can for him, but I don't want him to suffer.
I'm home now and have some pictures and a better description of the white areas on my boy. They don't look like open sores, but more like the 'skin' is coming off in two places - this is only on his right side, nothing like that on the rest of his body. His stomach DOES look a bit less bloated, though I still see no poop in the tank. He is also moving around a little more, but he still won't eat at all.
Regarding the picture, he takes after his owner and hates the camera. Every time one of us tried to take pictures he'd swim away. This was about the best I could get.
Do I need to try another kind of medication? I still have a couple of doses of Maracyn I and II to give him to complete that run. Should I look for something like the Kanaplex that was mentioned before?
The best treatment for internal infections is feeding meds for parasites or Kanaplex for bacterial.. or in the water.. in either rate a 2-4 week treatment is needed.
Try the pea again.. I wiggle my little pinky finger in the water until I get their attention and they are right up on me, then I drop tiny little pea bits right in front of their face. I have yet to have a betta refuse it, but it's possible I suppose.
He looks slightly less bloated. Since you have the Maracyns still, continue with those. With an external wound like that, sometimes the best treatments are either just Kordon Fish Protector or an antiseptic like Pimafix (used in a half dose).