Am I prohibited from exercising the privileges of my pilot certificate during medical deficiency?
Yes. You are prohibited from acting as pilot-in-command or as a required pilot flight crewmember during any medical deficiency that would be disqualifying or may interfere with the safe operation of an aircraft.
For more information, see 14 CFR §61.53
A simple problem such as a cold, a broken arm, or an abscessed tooth may require nothing more than the appropriate treatment and a little time before you can safely return to the skies. A more complicated problem or the development or change of a chronic illness may necessitate consultation with an AME or the FAA before resuming flying. New medical conditions do not need to be reported to the FAA until you wish to return to flying.