a) You should talk to a pro about this.
b) There are plenty of jobs that are a good fit for introverts, people with social anxiety, misanthrops, people who like to be alone, etc.
c) You feel overwhelmed right now but everything will be okay. Strongly consider point a) for actual help.
This sounds like a problem a psychotherapist could help with.
Sometimes you can solve it by talking it out with the peanut gallery, but... this isn't a mild case. It got you unemployed. It needs addressing.
Well, you ended up in what seems to me to be one of the worst possible jobs for someone with social anxiety. Unfortunately, it is also one of the easy jobs to actually get.
I agree with looking for help dealing with the anxiety.
Don't feel like a loser and isolate yourself over one (really) difficult situation. You said that you have had other jobs that worked out okay. So keep that in mind. It is a difficult challenge you have to deal with, but it doesn't make you a failure or loser.
As people have said you need to talk to a pshyc for this. But also you may find a profession that is less people crowded. Many professions give you office environments where you can get to know a few people and just deal with them. IT networking is one that comes to mind or programming. Both of those will give a structured interaction with reduced emphasis on people.
So you may have to grind college for a few years to get to a good career point for you.
1. You might not see this, but you are way to young for any of those things to be a problem. And not succeeding at one job, doesn't mean you couldn't at another. I once got fired within week one at a job :D
2. What is it what you want to do for work? The working life isn´t a sprint it is a marathon which means you should be well prepared for it and have a plan how to get to the end without wasting yourself before. I imagine it is though to get a job as a untrained worker so is a apprenticeship or something like that a option for you?
Its inevitable that you will have to deal with people if you are just getting out of highschool and want a job. Understand that in this world, no one can succeed by themselves, you have to socialize in order to have a happy life (its a necessary condition of life). Why get anxious about something that you have 0 control over. Youre not a loser, why would you even think that.
I disagree, i dont think you need to talk to a pro about this. You have to relax, keep calm and carry on. Pull yourself up by your bootstraps and get out there. "How to Stop Worrying and Start Living" by Dale Carnegie, get the book, read it twice.