My betta has been having a hard time eating for several weeks now. When he tries to eat his pellets or worms he cannot get them into his mouth. It is like he cannot get his mouth open wide enough and then he has to gulp for air which leaves a huge bubble at the surface of the water. He tries so hard and every now and then he can wrestle a pellet into his mouth but it is a sight. His tank is clean, I use sea salt and ick preventer when changing out the water- as well as a chlorine neutralizer....I have treated the water with antibiotics too. Does anyone have ANY idea what could be wrong?