You know what to do as do we all, when this happens: see a doctor. to learn what is actually wrong. Once you know what is wrong, you can begin to trace back to what is causing the pain.
Unless your driller is a physical therapist or trained in the science of your bones, tenons, ligaments and muscles, he can't truly help. All he can do is what many car mechanics do: suggest changes one by one until he and you luckily find a cure. You need more than luck here. You need to know what is actually hurting you.
It could be spans, it could be pitches or some combination. Since your driller screwed up to begin with (unless you are now doing something very wrong), I'd find another pro shop which is considered skilled in fitting hands to balls.