What the other guys said. It's almost got to be string creep, and now the bow doesn't fit you the same anymore, thus throwing off your form. Most likely the string has gotten longer, the drawlength along with it, and the weight goes up on the bow. The tune goes south.

I've kept up with this for quite a while and read that although Hoyt makes some fine bows their strings are inferior. Suggest you get a good set of aftermarket ones and things will not change near as often---like maybe never. Winner's Choice, Vapor Trail, Prostrings and others are preferred by many knowledgable shooters.