Hmm. His belly doesn't look swollen to me. His color looks better than yesterday's pic but I think he's still a little pale. You have a heater in there right, temp 78-80F? He's eaten so that's good. 2 pellets isn't a lot depending on what brand you're feeding. You could fast him for 24 hrs, give 1 pellet, then fast for another 24 hrs & see if that helps. you could also add pre-dissolved pure epsom salt. Other than one deco I see in the pic does he have other silk or real plants? I would give him something tall with kind of broad leaves he can rest on. I'm sure you've tested his water & all was good? The other thing you could try to see if it makes a difference in behavior is to turn off the filter for a little while. Some Bettas take longer to adjust & that could be him.