go to dentist ...a cancer screening (if not covered by insurance) is only about 50 dollars... they take a light and see if you have any lesions in your mouth that show up under the light...
i doubt that it is cancer it sounds slike a severe case of gingivits.....when was last time you seen dentist??.....
I think you should brush twice a day, floss once a day (at minimum), try a mouthrinse that is alcohol free such as crest prohealth and call your dentist.