I would first confirm that you are not taking any medications you could be reacting to. Then I would request a CBC (complete blood count) to see if you may be reacting to mold or some other environmental poison that is making you feel ill. If nothing shows up there, and to get that order you would have to see a doctor, I would see a therapist and be open about your free floating anxiety. A lot of people have anxiety and take medication for it as well as talk to someone. They just don't advertise it. Just know you don't have to live like this.
I used to get this when I was a teenager first away from home at university. Even reading about vomiting (I was studying medicine) made me have to put the book down and go and lie down. After many months I realised that I wasn't actually being sick, and gradually started to regain a little control. CBT may help you here as this is a very real and common condition called emetophobia and responds well to CBT.