Idk what’s wrong with me plsz give advice

I keep thinking about breathing to much when I eat. And always think I’m going to choke etc. then I end up going full blown panic mood.this has been going on for weeks and I’ve lost weight from this. I hardly eat much. And I’m constantly checking my pulse and afraid of dying. Yes I’ve been to the doctors and she look at my throat and said nothing is wrong with it.