I have had a twitching sensation in the upper left chest area which is intermittent and lasts for 5 to 10 minutes. Why?

Hi doctor,

For two days now, I have had a twitching sensation in the upper left chest near the breast. It is intermittent and lasts 5 to 10 minutes. Sometimes the twitch can be similar to pulse or jerking or can be sporadic jerking with multiple twitches. The twitching is painless. Few times today, I have had a dull ache in that affected area that will go away without touching it. Currently no other symptoms. Pressing the area has a slight dull ache. Placing my hand onto the area that twitches, I can feel the deep jerk sensation. I do have LBBB (left bundle branch block). Following below was a test of my Lexiscan I had at the hospital. Impression: Small fixed region of decreased activity at the anteroseptal wall with normal wall motion at this site. While this could conceivably represent a small region of the infarct, an additional possibility is a soft-tissue attenuation. No evidence of ischemia. Normal wall motion with an ejection fraction of 56%. Narrative technique: Using pharmacologic stress, the patient underwent standard sestamibi reinjection cardiac imaging with SPECT. 2 separate injections of 99M technetium sestamibi were given consisting of 12.6 and 34.2 mCi. Wall motion analysis and left ventricular ejection fraction were obtained. Indication: Chest pain. Findings: Fixed decreased activity is present at the anteroseptal wall. No additional perfusion abnormality. No regional wall motion abnormality is demonstrated, especially at the anteroseptal wall. Ejection fraction of 56%.