social anxiety

the feeling of wanting to say something in a group of people but holding back because you're scared of what people will think.
wanting to compliment someone but not being able to.
some people find it easy to put their hand up in class to answer a question or ask to go the toilet but for me it takes up every ounce of my courage to.
"people will stare at me"
"i can't do it"
thoughts constantly going through my head causing my heart to beat too fast.
and when the teacher picks on me, my heart beats in my head and my stomach drops.
overthinking is my biggest weakness.
"are they laughing at me?"
"are they talking about me?"
"is there something on my face?"
"do they think i'm being rude?"
"they haven't replied to my message, what have i done wrong?"
"am i annoying them?"
"i shouldn't have said that."
i want to change it, i want to get rid of it, but i can't.