If this problem has been going on for years, just changing your pitch or span may not help right off. You might have to take some time off, let the situation heal and then try to new drilling. Not sure how long, but I would take sometime off to rest.
One question that I have is do you also bowl during the summer? If so, then you are only getting maybe one month off during the entire year. You might want to look at taking the summer off and then see how it feels...
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T.J.
BOWLING IS FUN NO MATTER WHAT YOU SCORE. BUT A 300 IS ALWAYS NICE.
STRIKE ZONE, ONSLAUGHT & PYRO. STAND 22 AND THROW 10 OUT TO 5 AND CRUSH THE POCKET. AT LEAST THAT IS THE PLAN OF THE NIGHT...
GOOD LUCK AND GOOD BOWLING!!!