I have nausea and been vomiting for a month. Mental or Physical problem?

Hi, I’ve been having nausea and have been vomiting for a month or so now. It first started with what I think was gastric when my stomach would hurt if I didn’t eat, to loss of appetite and now constant nausea and vomiting. When I smell strong smells like food, cigarettes or even when I’m in a public toilet I get nausea and then I vomit. But just recently I have been lightheaded, very tired, irritable and have been breaking down a lot more emotionally. Is this something to do with my mental health? Or is there something wrong?