My middle toes are burning all of a sudden?

Consider. Nerve or vascular compromise. If no recent shoe wear changes, would be seen for eval. Systemic conditions which may cause or contribute include diabetes, hypothyroid or even syphilis, however these are not usually sudden in presentation.
Deserves a visit. To a podiatrist. Neuroma would be my first thought. My second thought would be neuroma. If the doc you visit feels it is the same, injection therapy is quite helpful.