Could too much exercise/stress cause svt, etc?

Maybe: If you have the underlying substrate. In other words, if you're prone to SVT, it could be triggered by adrenaline (during exercise or stress.)

Yes: Giving adrenaline or exercising someone is often how we bring out an SVT. The circuitry may be arranged, in some people, such that an SVT can occur, but most people will never develop an SVT with exercise. Stress does the same thing. Exercising is important, and SVT's can be cured with catheter ablation procedures; therefore, you should see a heart rhythm specialist for an evaluation.