I also wonder --do you use braces for your hand?

Continued imbalance of the flexing of only some muscles will
eventually lead to the tendons on one side shortening. When that happens it is very difficult to get back to normal.

I'd really find another doctor --perhaps one who is more trained in metabolic issues, to determine if you have a calcium problem.
If you are not taking some magnesium with all that calcium, then I'd consider it. Calcium is used to contract and magnesium relaxes. The imbalance of the two, may lead to tetany.

Search that word too. --tetany.

If you want me to look up drug depletions for you...either PM me
or put your list here. It is possible a drug you are using is contributing to this problem.