having trouble communicating

i always find it frustrating & frightening to meet new people and talk with others, even with some of my close friends. i feel self conscious around others & avoid starting conversations. when online classes started, i thought i'd be able to avoid that now, but it's still the same. whenever i'm called by the teacher to speak up, i feel sick and lightheaded. i once even had a breakdown because i kept stuttering & i was unable to answer a question in online class. i don't know what to do or how to cope with it. i need some word of advice.