Well, if you had a UTI and could tell your mom about that, this should be the same kind of thing. You're not sexually active so a bump is just 'another thing' that is happening down there. Tell your mom. You can say "I had that UTI and NOW, I have this painful bump". She'll ask where and just tell her. You have to have a go to person and your mom wants to be it. I'm a mom, moms want to help.
It could be a cyst, ingrown hair, etc. Keep fingers off it so it doesn't get infected. And if it doesn't get better, you'll need to see your doc. Hot to the touch and painful is a sign of something infected.