It could be just a stye. Basically a pimple on the edge of your eyelid. But if you’re worried, should probably see a doctor (if you can)

Just wait for your eye appointment. Looking up symptoms online always gives worst-case scenario results. Don't worry about anything you see online unless your doctor tells you to.

There are a lot of much less severe things it could be. There's really no reason to suppose it's cancer based on just what you've said.

It sounds like a doctor's appointment is a good idea if only because it's been causing you discomfort for a while, but don't let yourself worry about it if you can help it. It's really really not panic-worthy right at this point.

One time, my cousin, yo his eye hurt for like a day and then it just like fell out of his skull. Like the whole thing just pop came right out. We were like, "What happened, cuz!?" and he was like, "yo, my eye hurt, so I asked random internet strangers if it might be cancer. The advice I got was so bad, my brain just pushed my eyes out so I couldn't read anymore."

Go to a doctor.