Your new tag line also states a CBS and mithrax crab. Either of these could be the culprit but moreso the crab. In any event, they may only be guilty of making matters worse. As far as the star being in the tank for this long, acclimation shock is not always emmidiately appearant and can sometimes take weeks to show up. Given the 45 min acclimation time, I am more inclined to think that is the cause at this point.
If all the water parametrs for NH3
are zero and the nitrates are low and the ph
/salinity is good, the only other cause may be a yet unseen hitchiker crab or mantis.