What Causes Pinching Pain On The Nipple?

Since last night I am very worried. I never felt like this before. Till I was a healthy guy though I am lean and with no problematic health ever. At evening after a nap yesterday I felt a little pain if I pinched the lower inner side below the left nipple(just above where the lower tip of heart located) with my fingers. I am a 37 yr male of healthy habits and do pushups every alternate day. The pain was not much but I felt more of a mental discomfort. My breathing was normal too but later yesterday night before going to bed (1 am) I just kept having thoughts that I was going to have a heart attack and this thought kept coming and coming and I felt crying at some moment and I just couldnt sleep and stood up from bed and splashed cold water over my face to ease out a little bit before going to bed again..but I could not sleep till morning as I felt I might die in sleep. However there was never any heavy chest pain. After I woke up after 2 hrs of sleep it seemed to have gone after I began my daily activities . Now it againseems to have returned and I am feeling a little anxious coldness in my left leg