Do your shoes wear down more on one side? Is it tender also (when you press there is pain)? Are you diabetic?
The first differential diagnosis is metatarsalgia, which can occur because of the biomechanical imbalances. The other causes can be bursitis, Morton neuroma, and plantar fasciitis. You would need radiographic foot survey, bone scan (to rule out stress fracture), ultrasonography and MRI of the foot to establish the diagnosis. The treatment includes physical therapy, inotophoresis, phonophoresis, electrical nerve stimulation (deep therapy modalities), metatarsal pads, semi-rigid orthoses worn in supportive shoes and other orthotic devices.
Please feel free for your follow up questions.
There are few specialists whom you can consult and would be helpful:
2) Physiatrist (MD in physical medicine and rehabilitation, called as rehab medicine specialist)
3) Podiatrist (foot specialist).
You can consult any of them.