Hi, I had a cold/ flu around January, and although all the symptoms have disappeared, I continue to feel just under par (easily tired, sometimes slightly dizzy after climbing to my sixth-floor apartment (no lift). I am 65 and up to that flu I was quite active (less in the winter. though) with cycling and badminton, easily outlasting my (much) younger friends. But during my last cycle (about 70 km) I really felt that I had a lot less stamina and my legs seemed a lot weaker than ever before. The reason I am thinking that there is something strange going on is that my urine is far more often (dark) yellow than before, even though I do not drink less than before. This makes me think I am continuously running a very slight fever . Is it possible that the after-effects of that flu are still with me?