Don't let your guard down, Covid is still out there...

So three weeks ago I go into the hospital to have a heart cath and the next day I come down with chills, severe congestion, feel like warmed over death. Lasts about two weeks. Took two Covid tests and was negative both times. 68 yo, heart issues, COPD, and a few other old guy related complications. I can see how people with severe lung issues could be in trouble with flu, COVID, severe cold, pneumonia. Plenty of viruses, etc that can cause us harm. Do what you think you need to do.