I would suggest that if the pain persists for more than a week even after resting it, or if it worsens then have it checked out. Stress fractures hurt across the top of the foot and they never heal until you are put into a stiff soled shoe or boot for a period of time. A strain can heal, but a tendon tear most often needs repair.
If you "baby" it and it feels better, then that is a good sign. If the pain worsens or doesn't improve I would definitely have it checked out. Just my opinion!