One of my back teeth hurts, could it be from gum?

Could be... Tooth pain is best diagnosed by a dentist who has the ability to take an x-ray, examine the tooth area, probe the gums and then come to a conclusion. See a dentist to prevent your situation from intensifying. A little cavity is so much less expensive and less uncomfortable than a crown, root canal or extraction. Prevention is the real key in dentistry.
Yes. The pain could be related to gum you chew and to the gums (tissue) in your mouth. If you have pain from chewing gum, it is possible you may have decay in the tooth, or a loose or missing filling. Another possible cause of pain from chewing is that the tooth may be loose due to periodontal (gum) disease or an abscessed tooth.