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Did you have an xray done at the time of the original injury?
I have a couple suggestions. One is to have an xray done of the foot while you are pressing down on the foot (i.e. a standing x-ray). This is a good way to rule out a hairline fracture of one of the foot bones that might not otherwise show up on a regular film. The other is to see a podiatrist (i.e. foot doctor) and have the foot examined carefully for a neuroma. This is a painful ball of disorganized nerve tissue that can form after injury. A neuroma can be very painful when pressed, and can be surgically removed if necessary.
Unfortunately, the only way to "cure" a neuroma is to excise it (cut it out). If done by an experienced podiatrist or orthopedic specialist, the result should be the complete resolution of pain.