28 yr old female, experiencing swollen gum behind lower back molar- left side. Hurts mostly when touched. Never had bottom wisdom teeth, only the 2 top ones came in my early 20s. Could this be a wisdom tooth erupting? Swelling is in that area.

Swelling. In the location you describe swelling can be from over-erupted upper wisdom tooth, impacted lower wisdom tooth, food impaction, gum disease, draining abscess, virus infection, and so many other causes. To determine appropriate treatment the cause has to be determined. That means a trip to your Dentist is required for an examination and possibly x-rays. Please call now.
See DDS. Contact your dentist for a clinical and radiographic examination to determine if the third molar is present and the treatment plan.