Sounds like your draw length may be too long and/or you are shooting with too closed of a stance. Too long a draw length is a common problem that many bowhunters have and don' t even realize it until...slap. I used to have what I thought was a 30 inch draw length. That has shrunk to 28" over the years after going through the pains you are now experiencing. My arms surely didn' t get shorter. I can wear my heaviest hunting clothes with no arm slap and you should be able to also. Check your setup. Hope this helps. Jim