Hello and thank you for using HCM.I carefully read your question and I understand your concern.You shoud not worry about this . I will try to explain you something and give you my opinion.
Typical heart
chest pain have some characteristics. They usually are retro-sternal pains like squizzing , tightness or heaviness. They may irradiate to both arms, neck and jaw. They last from 5 to 20 minutes, might be associated with
nausea,
vomiting,
tachycardia.
In my opinion this isolated pains to left side near heart lasting for seconds are not related to heart problems.
They might be muscular, sceletic or neurotic pains.
The fact that you previously had muscular spasms fortifies my opinion that this might be a muscular problem.
So, you should not worry about. This is nothing serious.
Only if this symtoms persist and begin to bother you I would recomend some examination like an electrocardiogram, a cardiac echo and a strees test. This examinations can reassure you that its nothing serious about the heart.
Hope I was helpful.Wish you good health.
Best regards.