How can i tell if this is gingivitis? how can i tell if this is a canker sore?

Oral Health: Gingivitis is the inflammation of the gingiva (gums) surrounding your teeth It is usually generalized but can be localized to one area. An aphthous ulcer (canker sore) is a lesion that will present on your oral mucosa and although painful, will resolve on its own in about two weeks. From the symptoms you described it is best to see a local dentist for treatment while you still have teeth to treat.

Signs & symptoms: Signs & symptoms are not consistent with a single canker sore, although can indicate initial outbreak of herpes. Your problem seems to be from a bacterial infection, either of teeth, gums, or both, which requires professional care to treat. Sorry no magic bullet on the shelves in the drug store. Can also be from GERD, diabetes, blood dyscrasia, viral infection, etc. Please see your Dentist ASAP.