Cold sore on top lip and inside nostril, sore gums and roof of mouth?

An outbreak. : Sounds like you have an outbreak of cold sores. They do come in numbers sometimes and the best thing do is go to your dentist or md and get a script for acyclovir. If you are prone to these outbreaks or even singular sores..Then have some of that drug on hand at all times.

Sounds viral: This sounds viral. Likely a herpetic outbreak, but could be something more serious. Other conditions like erythema multiforma might be cause. I suggest a visit to either your family doctor or your dentist to evaluate sooner rather than later.