Tachycardic chest pain while sleeping?

I have a sinus tachycardia. My heart rate at rest is about 110-130 and gets up to 160 just running around getting ready in the morning. I get frequent chest pain and it's pretty scary. I also feel very tired and out of breath most of the time. My cardiologist hasn't found any chemical or physical reasons, just that I'm on overdrive all the time and can't really do anything about it. If I did calm down, I would probably pass out. The other night I was dreaming, and in my dream I passed out due to severe chest pain. I'm pretty sure I was actually experiencing the pain because it was all too real and I had another pressure, gripping pain a few minutes after I was awake. This is really scary. Does anyone know if this is possible or life-threatening (while sleeping like this).

Also, since I get pretty scary chest pains all of the time, how would I know when the pressure is enough to go to the hospital (otherwise I'd be in the hospital every day). Usually when I get these pains they last for a short amount of (scary) time and repeat a few times but not for long enough for me to feel as though a hospital would see anything by the time I got there. :( Any experience or answers to my preceding questions?