Is a 4th episode bad?

Okay, around 9 or so, about the time I was helping mom make dinner, I felt the faint tightening in my chest and coughed a few times as my breath seemed to get difficult. Mom and I were discussing it and have come to the theory that maybe it's the weight I've lost so quickly causing it? I've dropped roughly 20 pounds recently (not too fast, 11 pounds immediately then a fairly slow loss of the remainder). Not sure but going to keep an eye on it. When I checked my heart rate on watch it was actually lower than normal - about 53 rather than 60.