Popp, please use capitals at the beginning of sentences. Thanks. :)
I get a little sore there too if I do a lot of stretching. You might try a different grip aid than whatever you’re using. Powder and rosin can contribute to the soreness. So can cloth or paper towels. I get an exellent grip that’s easy on the skin by stretching immediately after a hot shower or bath. A good soak gives the skin perfect tackiness.
Try to better grasp the internal shaft instead of focusing all the force on the head itself. Grip the shaft about 3/4” - 1” behind the head and snug down the OK. When you pull forward the internal tissue will compress toward the head. Your hand will move forward to rest on the head, except the internal tissue will be taking more of the load.
Use some moisturizing lotion after the workout. Udder cream or a good hand lotion work well.
IMO, overhand beats underhand hands down!