Exactly the idea that comes to my mind.

I believe you are having what I have called, 'performance anxiety'. I think it stems from our tendency to expect too much of ourselves and need for things to go smoothly. Should you wish to stay the course, you may want to evaluate and alter your expectations.

In my own experience with food services it was the inability to count on a smooth operation that was my own challenge. I was very stressed out as I was constantly vigilant in trying to anticipate difficult and uncontrollable situations. I would then beat myself up for not being perfect and able to control those events. It sounds like you are encountering the same circumstances

After moving on from such employment I heard over and over just how common it was to have such an experience. You are not alone.

There are other ways to work in the customer service industry. Retail can be more rewarding than food services. It doesn't have the same level of stress. Being a cashier allows you to work with the public yet is more routine with less opportunity for stressful events to pop up. Customer service that has you working from behind a counter (for example being a bank teller) also allows you to work with people in a controlled environment.