Tightness/ stretch post workout. Again.

Dr, I'm Deepak 23YO,  was down with corona, RT CPR result was "Detected"  (not positive) I had a fever for a night on 6th August and i tested myself on 12th August. I had bad anxiety and panicked and didn't have any other symptoms besides that i just felt i couldn't breathe. However since then I'm unable to do any workout or even dance after hours or a day i feel stretch or tightness feeling in back and sides of the ribs. I have done X ray and ECG everything is normal, Dr said you're completely fit and fine you're jsut thinking about yourself too much. I dont knkw whether its anxiety post workout, cos I was very much concerned since August for my breathe. I do have allergic rhinitis though. My SpO2 levels is always 98,99. I do fear of working out now thinking this tightness will happen again.