Lymph nodes

So I have a small bumb behind my ear towards the lobe of my ear and haven’t noticed it before until today. Not that I would notice tho so it could have been there for days idk. But it doesn’t hurt and I’ve just had unprotected sex 2 nights ago.. I’ve looked it up and says I could have hiv in an extreme case..I’m just nervous but it’s so small like a pea size and you can’t even see it..I just don’t know if they are common or if it’s something I should worry about please comment your thoughts! I don’t know if I should wait a week or two to see if it goes away because that’s what it said online and then go to the doctors or if I’m okay and just overthinking things