The fin rot is because the water needs to be changed more often. You need to be doing 100% once a week and another couple smaller changes in between with that small of an uncycled bowl. Also, even though it's really good you have some kind of heater, 72 is way too cold. 76 is minimum, but bettas do better a little warmer around the 78/79 mark. The bloating could be constipation. Low temps slow down their digestive system and tend to lead to this. Also if the blood worms are freeze dried and you don't soak them before feeding, this can also cause bloating. It's also a good idea to fast your betta and not feed him/her one day a week.
Is there any pine coning or is it just a little swollen looking? Photo again would be helpful here.. For now I would up your water changes, find a way to raise tamps (Slowly, don't want to shock) and fast a few days while monitoring the poop. You might want to stock up on some pure 100% epsom salt with no dyes, perfumes or any additives (check ingredients label and CVS Pharmacy is what I've found in the past) in case there is any pine coning or he is not improving in a few days. Normally I would add aquarium salt to deal with the fin rot but I would not use AQ while there is bloating involved.. the epsom may also be helpful for the fin rot but I wouldn't jump into it just yet. Up to you. You could try as little as 1/4 tsp per gallon or as much as 1 tsp per gallon, predissolved in a little tank water before adding back.
Last edited by callistra; 12-04-2012 at 10:27 PM.