Fever, chills, fatigue & moist cough for 3 days with night sweats & I almost fainted while urinating which resolved after doctor prescribed amoxicillin & 3 weeks later again got the same symptoms just for 1 night and it resolved on its own. What is it?

It is either a... Either a coincidence or not a coincidence. One's primary care doctor can evaluate. A patient in such a situation should write down his symptoms in a calendar diary, in case this issue is hard to figure out later. If symptoms are not a coincidence, then they are from a recurrence or flare-up of a prior condition such as infection or inflammation. If a coincidence, then the two events are unrelated.