I am so sorry. I can relate to so much of your issues. I agree....your immune system probably is compromised. I just went for my 2nd i.v. infusion today with an integrative medicine doctor that treats Long Covid. It is to boost my immune system and help with my increased joint pain and upper respiratory issues since COVID. I think you are right. A lot of doctors truly are at a loss on how to treat long Covid. I have never been as sick a I was last year with Coivd and then this summer for 2 1/2 months with pnuemonia, asthmatic bronchitis & sinus infection & coughing from Long Covid. Levaquin was the gold antibiotic to clear me up and I had to go on 2.5 mg of Albuterol in a nebulizer 3 times a day which helped greatly. The humidity has been so hard here this summer and that made the asthma worse. I am much better now since the humidity is down. I am praying for you right now and that you get some relieve. Stay strong and encouraged. We need each other! Blessings & Prayers....