Lamictal and sweat

Took Lamictal for 4 months to treat schizoaffective disorder - in that time it completely changed my physical health. I went from a person who used to run 10 miles a week and cycle a lot, to not being able to walk for 10 minutes. The worst thing was the raising heartbeat, and the tightness in my chest and lungs. Lamictal messed up my lungs. It feels like I was smoking 40 cigarettes a day (I don't smoke at all). That's what it was like to try and run. I cannot run now and every time I do a gentle bit of physical exercise I am completely out of breathe, drenched in sweat and exhausted. I have ruled out anything else that could have caused this.