It doesn't look like a case of HITH, however, something you should pay attention to, It looks like in the photo that there is another depression to the left of the eye. See if the fish has anything matching this on the other side, if he does than he's probably ok, if not then it might be HITH or something else.
I agree with the other guys that you should focus on water quality for the next few weeks and see if things improve.
best of luck