Please help im worried this is cancer (probably a canker sore) but please help?

you're not going to get cancer from packing one lip. Just don't ever do it again or it will turn into cancer. Canker sores last a long time. If it's still there in a week go back to the dentist. Also tell your dentist that you used dip. It is really important to always be open and honest with your doctors so they can do their job correctly.