What is this faint constant vibration in my foot? i was tested for diabetes a year ago and results were negative never had gestational diabetes either

Nerve injury: It certainly could be a nerve injury. It does not have to be related to diabetic neuropathy. It could be something like an entrapped plantar nerve or damage further up your leg, say at your peroneal nerve and the branches that are most affected are those endpoints at the bottom of your foot. You could have an EMG done to rule out any other nerve damage and see if your plantar is entrapped.

Peripheral neuropath: It sounds like peripheral neuropathy. You do not have to be diabetic to have this, although that is the most common cause. I would suggest a nerve conduction study to rule this out. It could also be caused by a pinched nerve in the back, called a radiculopathy.

Nerve: Vibratory sensations are nerve related. It may be pressure on a nerve from a shoe or activity, or a damaged nerve. See a podiatrist for evaluation.