I can relate also. Not all hunts bring the same enthusiasm and I can remember specific harvests that didn' t give me the shakes, while others do. A kill that isn' t as clean as you' d like, a deer that comes out of nowhere that doesn' t give you time to get psyched up before the shot- both examples can bring out feelings like what you' re describing.
Hang in there. If hunting' s in your blood, you' ll come back around.

Good luck