Hi Doctors My friend is feeling feverish since sunday that is since 3 days, and mild tiredness , cold, nose stiffness. His medical history : He took booster dose of covid vaccine 40 days before. 10 days after taking booster days he tested positive for covid. He had 3 days fever, cold, n mild phglem ( normal like saliva) Recovered after 10 days of testing positive. It's been a month now since he tested positive he was doing fine with no symptoms . Now since 3 days he is feeling feverish and tired, cold But temp is 97.2-97.9 Please suggest what to do, what is the cause . Thanks