Elevated heart beat. Sinus tachycardia?

I played table tennis for 20-25 mins yesterday after 2-3 years. I don't generally have a workout just probably a walk of Hardly 1 km. After playing game I heart beat remain elevated for couple of hours around 100-120 sometimes reaching to 145 then coming back 110. I also had weakness in hands and legs and generalised weakness and anxiety. My oxygen levels remained intact at 98. I took concor 2.5 mg and slept in the morning I had HR of 70-75 but was feeling weak. But just 15 mins back I feel dizzy and my HR raises to 145 then came back to around 80-90 still in this bracket. Am I having any episode of ventricular tachycardia or what ? I am very afraid. I had coronary angiography in the past it was normal only myocardial bridge in mid LAD ? Should I be afraid of impending cardiac arrest or is it just a sinus tachycardia?