Hello, Donated plasma Thursday, felt fine the day before and of. (Had a huge spinach omelette right before) After the donation I slept over 13 hours and woke up with the flu. My fever hasn t broken and now, two days later, I m having back pains (possibly kidney area) and my skin feels bruised all over, with a non stop cough. I feel like I m keeping up with fluids just fine. When should I go see a doctor?