Mouth infection. Be valuable for me.

I hv lumps on bothe sides of my cheeks near upper jaws. I'm facing this problem since last 2.5 months. There was no pain at all. But last night I had pain on right cheek n in the morning while hvng breakfast I got swelling near my right ear. I visited ENT Dr. He said it's a kind of infection. He hs prescribed Mr some medicine for 5 days n said that if the problem doesn't get cured then he'll give some injections. I'm really worried about my problem. I can't concentrate on anything as I keep on thinking any my prob. Actually in my knowns I hv seen 2-3 cases of such condition which led to cronic disease cancer n then death within few months. Please help me put to get rid of this phobia. Your advice n suggestions will be valuable for me. Thanks