There can be many causes of pain under the ball of the foot. Pain under the 2nd MPJ is a common area for pain. This is called
second metatarsal overload syndrome and can result in capsulitis.
Capsulitis is inflammation of the structures around the joint capsule. This could occur in any joint, but in the foot it is most common at the metatarsal phalangeal joints (MPJs). The 2nd MPJ is the most commonly affected as it tends to take up the most pressure.
If the second metatarsal is longer than it should be, it will take up more stress and pressure when walking. This causes the tissues around the joint to become irritated and swollen and typically results in painful ambulation.
In many cases, excess stress placed on the 2nd MPJ is a result of
faulty foot mechanics. Excess flexibility at the inside of the foot, specifically the first ray, will result in elevation of the first metatarsal and transfer of pressure to the 2nd MPJ. A combination of a tight achilles tendon, which will transfer weight to the forefoot, a long 2nd metatarsal and hypermobility of the foot, can cause pain and swelling at the 2nd MPJ.
Because you have numbness and have experienced pain shooting to your toes, it is possible that there is a
neuroma. A
neuroma is an inflamed nerve in the foot and the symptoms can be quite similar to capsulitis.
Treatment is two fold. The first step is decreasing the inflammation. The motrin and steroid injection are both anti-inflammatories and icing will help decrease inflammation as well. The second step is identifying the problem and addressing it. This could be certain types of shoes, faulty foot mechanics or a structural problem, like a long 2nd metatarsal. Orthotics to control any abnormal motion, off weight the painful joint and distribute excess pressure are generally recommended (the shoe implants). Rigid shoes which will decrease stress on the ball of the foot are crucial. If the Achilles tendon is tight, calf stretches are recommended.
Conservative treatment is tried for a number of months before considering surgery. See this post for an example of a
shortening metatarsal procedure.