Long nose hawkfish acting weird

All of a sudden my long nose hawkfish is acting weird. Afraid he is dying. Had 2 other fish die but think it was because of the store I bought them from. The hawkfish I have had for awhile. Water parameters are fine. Tank is established 30 gallon with coral. He isn't moving much and when he does he is swimming crazy all over the tank. He is eating ok. He is hanging out by the overflow..pressed against it but he can move