I Started Having Twinges Or Electrical Pulses That Last Only

I started having twinges or electrical pulses that last only seconds. They are hard to explain, they happen in my chest and abdomen. They happen infrequent and during rest and activity. They are not painful just shocking, frightening, and unpredictable. What could it be? I have RA, osteoarthritis, and fibromyalga. I'm on medication for all of these.