40 year old female, healthy. injury to big toe = four yrs of pain all the time.no elevated uric acid ever, no swelling, not red. what could it be?

Nerve damage: You likely injured a nerve in the big toe (hallux) and developed a peripheral neuropathy, abnormal nerve function. You can get nerve function testing and there are several medications available that may help decrease the nerve pain.

Arthritis: Given a history of trauma to the joint, degenerative arthritis is likely. See a podiatrist for an exam, x-rays and discussion of treatment options.