Social anxiety and phobia?

i tried to go to a crowded shopping mall and i still feel scared of people! why am i feeling the same? i get so nervous to the point where i cannot walk properly. i freak out all the time and it seems people can tell that im nervous. im even too scared to stand up from a seat at a restaurant i just can't move. it's like i so scared that i froze and became stiff. what do i have to do?