I have strange fluttering in my right pectoral muscle (it seems). No pain,  I can see my chest move when it happens.  Its irregular, but this is the second day it has been happening.  No shortness of breath, dizziness or any other symptoms i can notice.
Thanks for your question on Chat Doctor. I can understand your concern. Muscular twitching, fluttering etc. are common in trace elements deficiency like calcium, magnesium etc. It is also common in vitamin d3 and vitamin B 12 deficiencies. So get done serum calcium, magnesium, vitamin d3 and vitamin B 12 levels. And if any of these is deficient than you need supplements. If all are normal than get done ECG to rule out arrhythmia because arrhythmia can rarely cause feeling of muscular fluttering. So consult doctor and discuss all these. Hope I have solved your query. Wish you good health. Thanks.