Sharp pain from my big toe shooting up to my back happens occasionally, what can it be?

Sciatica: Could be a pinched nerve from the lower back causing this discomfort. Recommend x-ray to rule out any pathology around the great toe.

Entrapment : Likely a nerve entrapment. Possibly from low back. Nerve conduction study would be helpful.

Nerve impingement: Something is irritating the nerve travelling to this area. Often it is a bunion bump that is rubbing against the shoe. There is a small nerve that is right under the skin and goes on into the big toe. See a podiatrist for an exam, diagnosis and care.