What type of mouth sore is this that's coming on my gums and cheek?

Viral: Apthous ulcers or herpes simplex(cold sores) ar e the two most common reasons. Apthous ulcers can be related to a vitamin b deficiency or a diet too rich in acid. Try a b complex supplement and see if the frequency decreases. Also if you have not seen your doctor, so so. If it is recurrent cold sores (herpes 1) then you may benefit form a antiviral medication.

Cold sore: Cannot see leison but usually aphthous type leison which is viral in nature and some type of stress brings them on. They last 7-10 days and once they start there is not much to do but wait them out. Sometimes ice oor other ointments can reduce the sorenesss and time to 4-7 days.

Needs to be seen: Mouth sores can from many sources, namely canker sores (aphthous ulcers) whose cause is unknown but related to stress & local trauma, or....Herpes (viral) more often than not is seen outside of the mouth, or trauma, or a host of other possibilities. You need to see a dentist to diagnose the lesions and then recommend appropriate treatment as appropriate if necessary.