Big toe pain one foot only. bunion?

Possibly: The two main problems that affect the big toe are bunions and arthritis (hallux rigidus). Exam and xrays can help elucidate the problem.

Maybe: If the pain is at the inside of the foot at the big toe and there is an enlarged bone, then yes you have a bunion.

It is possible.: It depends on the location of the pain. Have your foot evaluated by a professional and get the appropriate treatment.

Pain: If you are having pain see your podiatrist for an exam and x rays and a diagnosis and treatment plan.

Gout?: I will add an alternative answer here. One toe pain with redness and swelling can also be gout. This is a very significant pain, however, and usually is accompanied by swelling and redness. Gout is easily diagnosed by your family physician.