Sorry to hear you are sufferfing like this. Zoloft can make you feel worse at first but it does settle down and worked well for me for a year or two.

I think the most important thing is that several Drs have said you are ok. I am sure anxiety could contribute because it makes breathing weird but that you have been checked is the important thing.

Try to work on your anxiety now though. Many here will, like me, have had it their whole life sometimes managing well, other times struggling. The sooner you recognise it and treat it (the meds a good first step) the better.