I injured my hand and think i may have a stress fracture, will it heal on it's own or should i see a doctor?

Yes: If this was an acute injury (like a fall) and your hand is swollen, painful, and with decreased range of motion, you should definitely see a doctor. A stress injury/fracture usually happens gradually and will respond to rest. If you are not sure, i suggest that you see a doctor.

See a doctor: If you are concerned you should see a doctor although waiting a few weeks to see if it gets better is not totally unreasonable esp if the symptoms are not severe and you can use the hand reasonably well for light activities of daily living/ get you vit d level checked that's a good idea good luck.

Seek care: With that history, an x-ray will be an important test to help determine a course of treatmtne . I would seek the care of a professional that has the capability to evaluate and treat your condition properly.