I would be treating their food with metro as well.. Isolate and treat the water for any fish that is not eating, at this stage I wouldn't be worried about stressing them, yes it is good to avoid but in this case they may well die if you don't do anything.
The major issue with bloat is noone knows what causes it really, yes they know it is the bacteria in the gut and they know it is brought on by stress and tropheus are more susceptible to it. Diet is one of the "stressors" we can control and you are feeding them the best thing but sometimes other stresses occur, in your case it could be the breeding.. What size tank do you have them in? Or it could be something random like an ammonia spike that you didn't see or test for it is hard to say. Either way it doesn't matter but this is why I have seen it recommended that every tropheus keeper should have metro on hand to start medicating the second they notice a fish hiding to hopefully knock it in the bud.