Hi, Welcome to Health care magic forum.
The donation of the blood or plasma may not have any side effects like
dizziness, etc, of course rarely some people may have it, due to psychological feeling, if given for the first time.
Any how it is better consult your doctor, for treatment.
I advise you to have oral electrolytes, fruit juices, and other fluids.
Take more of green leafy vegetables, pulses, sprouts, and protein rich foods, to have a early recovery, and to have good resistance.
Wishing for a quick and complete recovery. Thank you.