Workplace Anxiety

I feel that the place my anxiety is the worst is at work. I don’t know why as it isn’t to mentally taxing and isn’t physical damaging for the most part.
I almost always dread going into work and am always fearful that things will go wrong. I am always afraid of making a big mistake that will ultimately got me my job. And with the economy being like it is right now very difficult to find as new one.I have to always keep a brave face and not indicate that there is something as this is not a place you want people to know you have a problem especially a mental illness.
There is a certain stigma in our society as this kind of problem can be shown as a form of weakness and could be costly. It has cost me pay raises and promotions. I am basically stuck in neutral right now.
I would like to move on but the fear is this will follow me wherever i go and as mention elsewhere I have had this problem at several other jobs. I feel it may be the job as I often feel I am in the wrong profession. I may have to seek out the right profession for myself.
I just wonder if this(Workplace Anxiety) is an separate issue or just a part of having GAD. This has been especially hard for me the last four years or so with no end in sight. I know it won’t last forever but it is a tough burden to carry.