Talk to your parents or o to the doctor's first and see what they say. Don't bother telling your friends, it really isn't any of their business to be honest, unless you really want them to know.

Dyslexia is one of those conditions that is hard to understand, so as Best Friend said, you probably should go to your parents first and have yourself checked out to see if you do have it. It might not sound fun, but when dyslexia slows down a student ability to take tests, they usually allow you to go to a special testing room and have extra time to complete your test. I imagine it's a little scary to have to deal with a condition you knew little about, but be brave and face it head on so that it doesn't get the better of you. Please give no worry towards the idea of people thinking you are lying, anyone thinking that would be quite ignorant. Hope you get things figured out!

I actually have dyslexia too! My father also had it. It really hurt him when he was younger and in school... but now he's actually a teacher and helps kids with disabilities, especially in reading! Dyslexia is particularly hard when you're in school (all those tests and letters! Ugh!) but it does get better. It's not something that will change your life irreversibly, it's just something you have to learn to live with and it'll make you stronger.

Don't be ashamed! I would recommend getting the help you need and telling anyone if it comes up.