Sounds like a definate tuning or form problem. Sounds to me that a good proshop is what you need. Problem is a good one is hard to find. A bad one can take you down a long bad road and have less than you started with.

I would start with paper tun at various distances, expecially 5, 10, and 15 yards. That usuaally tells the tale. The rest is fine tuning. Also don't shoot just one arrow while paper tuning. See bullet holes 3 times out of 3. If not, might have a clearance problem.