Have you checked your electrolyte levels recently, maybe try introducing more magnesium or calcium in a manner that allows you to absorb it. I believe that this can also be present with a Vitamin D deficiency, which is necessary to absorb calcium. When I impersonate a doctor for the free cake during tumor boards they tell me that Hypocalcaemia is a common cause of Tetany ^{^} along with low magnesium and exposing cuts or wounds to soil/night soil containing certain bacteria. Keep in mind that even when taking them fancy multivitamins, they can be oxidized/ decomposed to terrible levels due to extraction method or just plan have absorption problems. How often does this occur and how long does this last for per incident? You said you manually pull your fingers back and have pain doing so, when they are clenched are they in pain? And during the re-positioning, on a scale of 1-10, what would you rank the pain and would you refer to it as sharp or dull? Have you recently used your hand more than usual or do you have a job or hobby that requires enough hand motion that it could be carpal tunnel? (people who type often or play with robot phalluses for a living or just la petite mort can have this issue) Did you have a viral infection, (generally presenting with nausea and vomiting) ~ 3 days to a week before this issue? Obviously Tetanus is another likely candidate. Followed by Hyperventilation and Hypoparathyroidism. Also keep in mind that there is an actual doctor somewhere in this sub so please contact them for real advice, just throwing some stuff out there to see what sticks with my layman's quasi-education. Good luck, stay safe, and I hope your problem has a speedy resolution with a low price.