From a teen in the U.S.: I have been having headaches, slurring words, doubling letters, trouble focusing, blurred vision and sometimes losing it. I have been having this issue for a while with a bunch of symptoms combined. They didn’t worry me but it hasn’t gone away and my headache is constant. I get words and numbers mixed up and have been having worse communication skills.
You may not be “worried” but I am. Get yourself to a doctor immediately. These are not, not, not usually symptoms of mental illness. Symptoms like this are your body’s way to tell you that something is wrong and that you need medical help. If you don’t have a medical doctor, start with your school nurse. If the school doesn’t have a nurse, get yourself to an emergency department in a local hospital.
Ignoring warming signs does not make a problem go away. Responding early generally keeps something from getting worse.
I wish you well.