Well, first, I hope that you are seeing a professional to check you over to ensure that you don't have any type of virus / flu, etc.
Then, if it is anxiety, that you can see a professional counselor to help guide you in management techniques.
Anxiety brain and the gut are intertwined in the nervous system . . .whenever I have anxiety. the stomach is the first to tell me and often it will feel very hard because the muscles tighten up during anxiety . . . .
Also, the less you eat, the body goes into starvation mode and sometimes the ability of the gut to function in a normal way gets out of whack . . .
All of this to say . . .if a doctor says you are physically okay and that it is anxiety, then you need some management techniques . . . anything from meditation to gentle exercise such as walking until you get used to it to reintroducing food back into your system . . . for example, if you have not been eating for a week, then don't go out and have a 5 course meal . . . this will overtax your system . . . start off with small meals and build up and make sure you drink water to stay hydrated . . .
But, really, you need a check in with a med professional and go from there . . . and, of course, come here as often as you would like to check in and let everyone know how you are doing . . .take care, kc