mystery disease

Question
I took in four bettas this past fall after my animal behavior class was done with experiments.  I have two 2.5 gallon tanks, each with a clear divider and a male on one side, a female on the other.  They each have a light and a Whisper Bio-bag filter.  I use Tetra EasyBalance to reduce water changes.  They were being fed Tetra BettaMin Tropical Medley, but when one of my females started to look bloated, I switched their food to Hikari Betta Bio-Gold pellets.  I put API aquarium salt in the tank and treated both tanks with Maracyn and Maracyn-Two.  My female continued to grow in size, and just died last night.  Now I'm worried that my other female is starting to bloat.  I have no idea what's causing this, because I've switched foods and treated with antibiotics.  Their tanks are clean.  The female that died had plastic plants, the other has live plants.  I even tried feeding the one a mushed up pea for constipation, but it just sank to the bottom of the tank and she didn't touch it.  I'm also wondering if I should take out the divider in the her tank so the male has more space since she's gone, but I don't want him to get sick.  The weird thing about this disease, or whatever it is, is that it doesn't match anything I've found online.  Her scales never stuck out like a pinecone.  She continued to eat until the last day, and she slowly bloated for about two months.  At first I didn't even notice, then thought she was pregnant.  And I don't know if this is normal, but both females had a white spot on where I assume they go to the bathroom.  After the one female died, I gently probed her gut, and while jelly-like stuff came out where the white dot was, and seemed like the dot was really some of the white stuff coming out.  The remaining female still eats like a pig, and both males are eating, though they seem a bit skinny.  The one with the remaining female builds huge bubble nests.  The other one hasn't built on for a while, even with the female alive, though he did flare and show off for her.  He also seems to have a hard time getting pellets in his mouth, so he's being fed the flakes.  One last note is that they have been on the new food for a little over a week now, and today I noticed the male with the living female had a long line of excretion hanging out.  It fell off while I was feeding him, but it seemed to resemble the shape of intestines, and contained a whole pellet.  It was like he just emptied the whole contents of his gut.  Is this healthy?

Answer
Hi Ella:  Try to feed your bettas live food... like brine shrimp and tubiflex worms and some pellets.  Your betta may have intestinal parasites or even worms... so you can treat them for that.  The live brine shrimp will help also as they tend to be a form of laxative.  Betta only live for 2-3 years so its hard to say what actually killed your female... it may have been a parasite or bacterial infection or just old age... long strands of poop are usually a sign of intestinal parasite... best course is a dose of medication that goes on the food...  keep me posted.. dave