Jessica HR/O2 Issues

I went to my Dr today for what I thought to be a follow-up. I ended up in the hospital having an emergent CT Angiography.
I've been having problems with shortness of breath (to the point I can't talk when in motion), chest tightness, dizziness, a floating feeling. It's increased when I walk up stairs, several feet, or get up and down. It's been going on for about 2 months. I wasn't concerned necessarily, but it's not getting better and ridiculous that a 24 y/o who doesn't smoke and is not overweight can't walk up 5 stairs w/o feeling like my chest is going to explode. So, I thought I'd tell my Dr today. Apparently it's not a good thing.
We did an EKG, chest xray, and labs in office. All were normal. (Haven't had an xray since my surgery in April- that was interesting to see!) So, before I left she put a monitor on me and wanted me to walk around to see what my O2/HR were. We walked about 15 steps and my HR went up to 129 and my Oxygen dropped to 80%. Needless to say she wasn't going to let me leave then. She called the hospital and sent me over there immediately. I've not had the contrast experience before and mine wasn't a great one. My Dr called me herself an hour after the test- I do not have a pulmonary embolism! So, she is going to schedule a Stress Echo-cardiogram and wants to do a Holter monitor for 24 hours. With the rule that if things get worse tonight I go to the ER.
My Step-Dad is a Respiratory Therapist so he brought over his little O2/HR monitor for me to keep a log for the night. My Oxygen has been crazy as well as my Heart Rate. O2 has been anywhere from 74% to 99%. And my heart rate goes from 98 to 125. (My average in the last year and a half has been 80)

So, would you keep both Logen and I in your prayers as things have gone nuts in our house?!?!? Thanks :)