Help!! Dropsy

My goldfish has suddenly started to "pinecone" ---- looks like dropsy. I
have no idea what may have caused it except that the water hardness
suddenly went up. The fish has resided in a bare-bottom 5-1/2 gal glass
tank with no other fish without any problems. Water is changed every
other day since there's no bio filter.

I've been feeding Medikoi (has Romet B) medicated fish food, raised the
temp to 84.5F, added epsom salt for 2 days now. But I notice thin
clear, slimy threads coming off her body. Not a lot, just one or 2
threads every once in a awhile. I don't know if this is a sign of
getting better or worse. Should I add an antibiotic to the water?