What Guys Said 1
One possibility is that his problem has nothing to do with your relationship. Sometimes, people get physically sick, but don't understand exactly what's happening to them because the symptoms are unusual. So they freak out a little, and it creates a horrible cycle: their anxiety makes them worry, and the worry leads to worse symptoms, which leads to more anxiety. Happened to me a few years ago. For a month, I thought I was having panic attacks: seemingly out of nowhere I'd get dizzy, my chest got tight. It was terrible. But it turned out that I had an inner ear disorder that messed with my balance. My doctor said it's very common for people to spend a lot of money on therapists and counseling in situations like mine. Your boyfriend might want to visit a doctor for a full physical exam, blood and urine tests, and so on. They might discover any number of problems that could lead to symptoms like you describe.
What Girls Said 1
I think it sounds like he's in love. Love can make you feel pretty weird at times.