I concur with Ken. While it is a good idea to look at autoimmune causes he is right that there can be a lot going on and all issues should be ruled out. I am a tarsal tunnel gal and had to have surgery for that, but many, many cases can be treated conservatively. Over use, exercise, shoes with too aggressive an arch can all put pressure on the tarsal tunnel and cause the symptoms you are describing.

Podiatry is a good resource as is Foot and ankle orthopedics or even Physical Medicine and Rehabilitation. I see a PM&R doc who is a whiz at ultrasound guided injections. They sometimes will do a steroid injection to "bathe" the area and decrease swelling and inflammation both in the tunnel and around the nerve. Physical therapy can help too.

I hope you find relief soon!