Need help I hate life

Basically I had an appointment at the job shop today and was feeling rubbish and anxious so booked it for a later time. I was still feeling the same but thought to myself what I always think that I can't keep getting out of things and that this is life. I was scared of feeling worse when I got there. Anyway i went, qued up and was anxious enough then this woman in front of me said 'oo you look small how old are you' I said '21' and she said 'I can't believe it'. I do look about 14 but anyway I could tell she had some sort of mental problem as she was talking rubbish to everyone else in the que. Ive not a clue why but this made me feel worse and I was just tensed up for 20 minutes waiting for my appointent wondering if I was going to faint. I couldn't stand seeing everyone etc and was all hot and dizzy inside and my stomach was hurting so I sat down. Anyway I kept telling myself Id get through it and feel ok on the way home and I did.

Ive been for appointments before and not felt like this but a lot of the time I do it so it can't be a specific phobia. Im supposed to be going on a training day in a few weeks for a job taking care of people with mental problems, some good I will be if I freak out like this! Anyway I don't know how im going to manage the training day let alone the job! I can't bear the thought of feeling like this on and off all through the training day its really not worth going. But if I don't go it means im pathetic, lazy and my parents will go absolutely mad as im supposed to be getting my life sorted out.

I just wanted to ask why did I see the whole experience of today as terrifying and strange, the people freaked me out as well. Has anyone any advice what I should do about this training day?