Occasional vibration under left rib age while breathing laying down?

Fasiculations. Muscle spasms, (fasicularions) can b from electrolyte changes, diet or those w heavy exercise (which can also inc Lactic Acid in muscle ; cause sim feeling.). If assoc exercise, back off intensity, inc freq ; fluid to help rid body of built up acids. If occurring randomly look at your diet. If u r like most us teens more fruit ; veg also good. Back or GI can also cause sim symptom. Feel better.