LOSS OF SENSATION IN BACK OF MY HEAD

I am a Post MVR patient . From the time my operation was completed i lost the sensation at the back of my head but i am having severe headache is it any complications of surgery or because of the sedative drugs which were given to me at the time of operation . they said that i was in ICCU for almost 10 days after the surgery and 4 days on ventilator with sedatives and ionotropes . please help me how to regain the sensation and reduce my head ache

any suggestions are appreciated