Do not worry about the temp. While I wouldn't keep the calico BN's in very high temps forever, it should not be what's causing them to behave mysteriously. I was told a couple of years ago that calico BN's are more fragile than other BN's, so after I lost my first 6, I decided against breeding them for a heartier BN species. When summers are very hot here in NJ, my cold tap water comes out at 84 and that is what my tanks containing BN's are....they don't skip a beat. Always with higher tank temps it's adviseable to keep extra air going into the tank.
From my experience with different sorts of BN's, their gills seem to be extremely sensitive to both ammonia spikes and nitrite spikes. They probably received a bit of a gill burn with your ammonia spike. Luckily for plecos having issues like this, they can stick their noses out of the water and breathe air that way too. It is very important at this point that you monitor that tank to be sure neither the ammonia or nitrite begins to rise again. If either one does, do an immediate water change to get it down, and do a SLOW refill of same temp. water, splashing it against the glass of the tank or your hand to offgas it as much as possible.
From my experience with different sorts of BN's, their gills seem to be extremely sensitive to both ammonia spikes and nitrite spikes. They probably received a bit of a gill burn with your ammonia spike. Luckily for plecos having issues like this, they can stick their noses out of the water and breathe air that way too. It is very important at this point that you monitor that tank to be sure neither the ammonia or nitrite begins to rise again. If either one does, do an immediate water change to get it down, and do a SLOW refill of same temp. water, splashing it against the glass of the tank or your hand to offgas it as much as possible.
