Hmm, wish oldfishlady or someone would stop by, since I'm still sort of a betta-disease newbie (not to fish in general.) I'm thinking...what would I do with what I've learned...for stringy poop and normal behavior...
Ok, I'd try adding epsom salt to the water. It clears out the digestive system and has, as some have said on here, a weak antimicrobial or antiparasitic effect. You can search on here for more information on that. Discus people use it to clear the way for medicated foods. In any case, it can't hurt.