Having had a few failed BTA's prior to the one I have now which has been with me for a couple years, I would say leave it alone. If there is plenty of lighting, it should be fine. I couldn't tell how long you have had it, 2 weeks? Light acclimation is a big deal, if it is new to your tank, much less changes to alk, ph, etc. At any rate, if it won't eat or cannot eat, your only real choice is to wait it out. There is no magic bullet for getting the animal to do what we want it to when we want it to, they tend to have their own time line ; ) The pic looks ok to me, tight mouth is good, through they will deflate and look terrible when they, shall we say, expel their waste. My vote is that it be left alone unless it starts to shown sign of physical deterioration. This I learned when on my 2nd attempt to keep a BTA, only later did realize, I most likely removed a perfectly healthy BTA from my tank because I was so paranoid it would die and 'poison' the rest of my stock. What ever you decide I hope you will go slow, keep your tank parameters in good shape and observe before you act.
Happy Reefing!