Most likely you have a canker sore or you bit your lip, so don't start panicking, but I would get it checked out if you're concerned. But definitely stay away from tobacco -- the pesticides alone used in tobacco will harm you let alone the other harmful effects of it. There are approximately 55 applications of toxic chemicals in tobacco farming, so we've taken a product used occasionally in ceremonies by American Indians to a product used all the time and then made it even more toxic just for fun.
The clear bump looks like a mucocele, but it looks like you might have the start of leukoplakia (precancer), so this may be your last chance to avoid oral cancer. You should avoid all tobacco, sugary foods, and try drinking green tea with mint to help heal. See a dentist or doctor for a thoughough checkup.
Yes! Your concerns are valid! It's best to have it checked! Good for you for tossing the tin!!