EMS503 you make a good point about going back to the original food and making a water change, but...
I've got to disagree with lowering the temp, we already know that changes have been made to the tank, and the occupants are acting different. Lowering the temp will only serve to increase stress levels. 72-74 degrees should be the minimum with the livestock that fishby indicates, and with unusual behavior and discoloration of one fish, an increase in the temp to 76-78 could serve to reduce stress.
The food change could be the culprit as red streaked or hemorrhaging fins are a common indication of vitamin A deficiancy along with loss of appetite and poor growth. But this would take more than just a few days to appear. Also, the enhancing food could create the red coloration but it seems it would be present in both Bala's.
Red streaked or hemorrhaging fins could also indicate ammonia poisoning, septicemia, dropsy or several other diseases.
I would as ems503 said earlier change the food back, do a partial water change, but leave the temp as is or raise it slightly then observe. If the situation worsens or spreads to other tankmates, you should get info on some of the problems I've listed and follow a course of treatment for the one that matches your symptoms.
Hope this was some help... 8O