I recently started bowling a lot again lately and have developed a really bad blister on the inside of my middle finger at the first joint. Last night it got so bad it started bleeding and I couldn't bowl anymore. I'm trying to figure out what's causing this and think it might be related to my finger pitches. I use oval grips that are snug but not overly tight, so I don't think that's it. Is there a common fix for this with lateral pitches? When I look at the curve of my fingers, my middle finger seems to curve inward, so I'm thinking less left pitch may be needed. Any input would be appreciated.

Would something like this be indicative of the span being too long on that finger?

I've noticed some muscle soreness in that finger as well. I'm going to look into a slightly shorter span and pitches for my middle finger. Thanks for the feedback.

I'm going to try shortening my middle finger span by 1/16 and use the recommended finger pitches from the Morich fitting guide. According to that my lateral pitches should be 5/16 Left and 9/16 Right.

If the blister is on the inside of the finger it is most likely do to the pitch being too "steep".  The finger pitch will need to be increased. 

The finger muscle hurting would indicate an issue with either the span, the forward/reverse pitch or both.

If your PSO is just changing by an arbitrary amount then I would change PSO.  That person should be looking at your hand, ball and then measuring your span and adjusting accordingly.

By too "steep" do you mean too much left pitch or right pitch on the middle finger?

Turns out narrowing the bridge width to 1/4 and shortening the MF span by 1/16 fixed the issue. Crazy how such small changes can make a big difference.

Just curious if you narrowed the bridge to a 1/4" what was it to been with? 

Vulcan death grip...you were applying undue pressure on the tendons as well as digits