My pack is a Cabelas XPG 4000 IFP, I have done 3 -10 miles with this pack on with 20 to 50 lbs, as I am training for a 100 miler... BUT this pack is rubbing the top part of my keister (ass)in two quarter size spots that are in the same spot about 5 inches from each... This could be a big problem leading to infection on the trail. What can i do?