My brother's heart and lung health suffered extensively after his second bout with COVID. O2 uptake is somewhat diminished, and resting heart rate is still very

My brother's heart and lung health suffered extensively after his second bout with COVID. O2 uptake is somewhat diminished, and resting heart rate is still very high. Walking up two flights of stairs requires a 5 to 10 minute sit down as he is completely winded by the time he gets to the top. If any of that sounds familiar, you may want to get some more extensive tests done. I don't know what will come of it, pretty much the only thing that has helped my brother so far is a regular low dose of Benadryl. There's a bit of edgy research or internet driven anecdata (not sure which) that led him to try it, but it is better than nothing, at least.