Interesting.
BJD usually takes a head at a time, without mercy. That your single head didn't die suggests that either you didn't have BJD or else the movement from DT to QT somehow allowed the single head to survive BJD, an amazing report if it was sick.
I suspect that the single head may have been taking a dump (brown cloud from the mouth) and that it didn't have BJD. IF it wasn't taking a dump, it fought off the BJD and would seem to have shown immune reaction that allowed it to live (Novel report.)
I would put the torch back into the DT and observe how it reacts, and assume that it will not have a relapse/ die from BJD. Keep the Cipro handy in case BJD does appear, but I don't think that was what your torch was dealing with.