Could my cat possibly have a tick?

Near my cat's mouth, there is a small, round, black bug. We just took him to the vet last week, and we were told that ticks are more active this year than ever before. I'm worried this may be a tick. We've tried to pull it off, but we couldn't. So we got tweezers and when we tried to pull it off, the cat just cries and the bug doesn't budge. Its legs just squirm a little. We thought we may have been pinching the cat's skin, but we're pretty sure its the bug causing the pain because he keeps licking and pawing at the bug and rubbing his mouth against the wall.