I'm a writer and illustrator of children's books. After working for several hours, I've have trouble getting all of my fingers to straighten out. I'm in my mid-30s, so I don't think it's arthritis. What are the other possible conditions that could cause this problem?
You may have a simple case of trigger points (TrPs) of the muscles from overuse or chronic contraction without relaxation. Trigger points are tender spots in a taut band of tissue (usually in the muscles or fascia over the muscles). When these hyperirritable spots are pressed or compressed, they cause local tenderness and referred pain. The history you present with chronic use and overuse of the hand lends some support to the idea of trigger points. Fibromyalgia is another (different) problem that can first show up as a symptom of similar muscle problems. Usually there are a wide range of other accompanying signs and symptoms such as cold intolerance, migraines, hair loss, poor sleep, and many more. A more local problem could be something called Dupuytren's disease. Dupuytren's can cause a contracture of the fingers. The palmar fascia (connective tissue of the palm) contracts, or tightens. This contracture is like extra scar tissue just under the skin. Without treatment, the contracture can become so severe the finger no longer straightens. It most often affects the ring or little finger, sometimes both, and often in both hands. If daily stretching of the fingers and muscles of the forearm don't help, see your doctor. There could be a medical cause for the problem. This should be ruled out and an accurate diagnosis made so that proper treatment can be started.