Starting yesterday evening around 8 p.m. I began feeling a pinching sensation on the right side of my chest. The sensation lasts approximately one second or less. No continuous pain, but the pinching sensation recurred in approximately 10 - 15 minutes thereafter. Most of the night I didn't feel it while sleeping. Same sensation started again this morning around 4 a.m. No shortness of breath or other abnormal physical problems. Do you know what's possibly causing the twitching sensation mentioned above? Thank you.