I have a problem & I'm very scared! I've had a heavy vaginal discharge & pain (like menstrual pain) for a couple years now. Is it cervical cancer?

Could be many things. The symptoms you describe are not specific for any entity, but certainly warrant a visit to either your primary care provider or ob-gyn. It also would be prudent to have regular pap smears.
Doubtful. If you have been seeing your gynecologist yearly and getting regular pap smears, it is unlikely, but not impossible for you to have cervical cancer. At your age, it is particularly important to have a comprehensive gyn exam and testing to evaluate your pelvic pain and discharge. It is not normal. . Please make an appointmenmt with your gyn asap.
Had a Pap smear? If you are seen annually by your gyn or primary doc who should be performing breast exams, pelvic exams as well as pap smears, then the chance of these symptoms being caused by cervical cancer is very very low. A pap smear should b able to determine. Sometimes GI problems can b the cause of similar symptoms other than vaginal discharge. Crrvical cancer could cause symptoms once advanced. See gyn.