this has been happening to me for a few years, and though very infrequent, i am scared
Chest pain with shortness of breath and sweating are very classical symptoms of abnormal heart condition. The pinching sensation you're feeling could be from a number of different things such as esophageal spasm, lung irritation, acid reflux, musculoskeletal pain, or heart condition. Regardless, I would recommend having your heart checked out again. It sounds like you might need an EKG and or a stress test. You could be having arrhythmias which is causing your heart to beat fast and abnormal.  The racing heart could be giving you the pinching sensation.