Gout is definitely a possibility. This is a condition in which uric acid crystals build up in the joint space and lead to periodic flare ups, which are characterized by redness, warmth, and pain in the joint. Gout is often diagnosed clinically by doctors (meaning that they just examine the joint and diagnose it as gout based on the pattern of inflammation). However, in cases where there is some doubt, it is necessary usually to withdraw some liquid from the affected joint to confirm or rule out the diagnosis. Some primary care doctors
perform this procedure, as do most rheumatologists.
It is also important to rule out an infection in the joint, especially if the symptoms are not getting better, or if there is fever or other serious symptoms. Once again, aspirating some liquid from the joint space is the procedure usually used here.
Finally, this could be a "stubbed toe" if you can recall a recent injury to the toe. If there is a history of trauma then it may be necessary to perform x-rays to rule out a fracture.
Start by seeing your primary care doctor
or a rheumatologist
again as soon as possible. They will be able to help you decide what to do next.