Okay, sorry to hear that. You could have an abscess, especially if there is a foul odor, bad breath, or drainage from the gum. Gingivitis or other gum disease could also play a role, although this often involves more than one tooth. Another possibility is that a tooth is impacted - that is, it cannot break through the gum properly and becomes stuck (as is common with wisdom teeth).
Contact your dentist or other healthcare provider right away!
Just one more question.
Do you take a medication for osteoporosis or other bone disease, such as alendronate (Fosamax), risedronate (Actonel), ibandronate (Boniva), or the intravenous medication zoledronic acid (Zometa or Reclast)?