Waking up short of breath, sweating and heart racing or beating slow/hard. Also constant tachy. Doc just says stress but I know theres something wrong?

Panic attacks. I assume your cardiac workup is negative? Panic disorder can cause such attacks in sleep as well as daytime, but some have them more at night. It is more than "stress" alone because the episodes may seem to come out of the blue, with no clear trigger. There is still good treatment with a combination of medications and psychotherapy. http://tinyurl.com/32guos.