Not sure if Social Phobia or Anxiety

Hey All i was just wondering im not sure if its social anxiety or what but when i was growing up i was always popular had lots of friends went out all the time to parties and was a leader when i became 17 my mood changed and at school i would avoid friends and people in the hallway i became more quiet and now i hardly go out to parties or see my friends i hate being alone with a friend but if theres a group i feel a bit more comfortable i have a amazing boyfriend who im pretty comfortable with i hate looking in his eyes when we're talking i feel uncomfortable or eating in restaurants or with his family i get REALLLY nervous!! Around certain people friends im alright but around others i dont wanna see them I went to my Dr. and he prescribed me ciraplex will this help?
i just dont get how all the sudden i went from being funny a leader and sociable to a scared quiet nervous person is there any prescriptions for social phobia?