I have developed an issue over the past couple of years, and after going through several changes in span and pitches, I've seen no improvement.  Im at the point now, that by game 3 of a typical league night, its sore. 

By the looks of my thumb, I would say kung-fu death grip.  However, I have been concentrating on not squeezing and having a "soft" release...  Perhaps I'm doing it and not even realizing it?

The symptoms are a a very sore thumb nail, about 2/3 of the way towards the end of the nail...Dark underneath.  I have a matching dark mark at the same position on the pad side of my thumb.

I don't have any crazy pitches or anything...  Span is 4 5/16" thumb pitches are 1/8" left and 1/18" reverse.

I tried to take a few photos after league tonight:

http://i1012.photobucket.com/albums/af243/sberkhous/Mobile%20Uploads/IMG_20151203_222529_zpstp0rbnc6.jpg

http://i1012.photobucket.com/albums/af243/sberkhous/Mobile%20Uploads/IMG_20151203_222551_zpskxervgeb.jpg

Anyone ever see this before or have any suggestions? 

Thanks,
Scott

Strapper,  one of the most ignorant ideas circulating is away pitch in the thumbhole.
Run, don't walk to your proshop and get your thumbholes redone with either zero or at least 1/8 under pitch in your thumbhole.  Temper this with the correct span.

Thanks for responses.  Span looks good right now (to me).  With my thumb in the ball, edge of finger holes is 1/2 to 2/3 of the way between creases, towards the nail.  Thumb holes are initially drilled a little big...I tend to have a wide, flat thumb.  I don't have the option of ovals, so go a little larger size and use tape.  Maybe this is the issue?  I generally have to put in a few pieces of tape to start the night and as things warm up, I have to take them back out.

I am speculating here and I don't like to do that without seeing what is going on in person.  A qualified pro shop professional would be your best bet for looking at your situation and figuring it out.  With that being said, sometimes that is not an option. In my opinion your thumb is wedged in the hole with the edge of the hole pressing on the base of your thumb and the back of the hole pressing on your nail as you come out.  This is typically a combination of the span being a little long for some reason and the hole size being a little large.  If you have not had trouble in the past, the first thing I usually check for is warn out inserts in the fingers.  Warn out finger inserts tend to allow you to stick your fingers in too far and stretch your span.  It is also possible a little shorter span or a slight pitch change is necessary due to a flexibility loss in your hand.  I would check the inserts and make sure your fingers are not going past the first crease, then I would pull straight back with your thumb and roll the ball on your right hand using your left.  The key is to take your thumb to the ball not your ball to your thumb.  Be careful to pay close attention to where you feel the ball coming off and on your thumb.  At this point you want to use tape to tighten the hole in any loose areas to make sure it is very snug.  Roll the ball across the carpet before using it on the lane to test for dragging and to make sure you can get out of it. At this point you should be able to lane test it and see if any of the adjustments help.  If not you may need a little shorter span or some pitch adjustments.  The halfway to two thirds between the creases is a guideline and depending on other factors shorter is sometimes needed for the hand to be relaxed.

As mentioned above. It is important that you learn how to properly tape your thumb hole as well.  Makes all the difference in the world when it's done right

Thanks everyone... Good articles!  I can remember reading them at one time for another, but never together and never back to back! 

After double checking spans, middle finger seems a touch long...after the hanging the ball straight down test, it seemed like I needed to squeeze a bit more than I had thought to hang on! 

I'm going to play around this weekend to try out a few small adjustments...  Always looking for an excuse to drillbup something new :-)

Thanks!

Does anyone make 1 1/4" outside diameter oval slugs in 29/32"?  Vise in that size are 1 1/8 diameter.

I know I've posted this before, but after years searching for the perfect feel in my thumbhole I've found that taping the part of the hole where the sides of your thumb (front or back or both) lays, gives you the firmest feel and I never grab and in turn knuckle the ball. My thumb shows absolutely no signs of callouses or damage to the nerve at the base of the thumb. I see wild swings in the size of my thumb due to living in WI and have found this really works well for me. I never liked tape directly under my thumb as it toys with your span and how your thumb lays. Tape on the sides gives you a barely negligible feel, but firm grip. There are no rights and wrong to the game of bowling when it comes to fit. Do what feels best for you!