My husband is having same problem. In 2022 had mild case of Covid. Immediately thereafter developed POTS , w/i 2 month period of time 2 transfusions of 4 bags each time. October 2023 diagnosed with Multiple Myeloma been on lenilomide $ dexamethadose …can’t sleep at night, breathless even when using oxygen and very weak. Sleeps on and off all day. Oncologist doesn’t believe it’s MM drugs but no one sees connection with or will admit to long COVID being cause