IST among other things

I need some help. I am 33 and was diagnosed with intermittent 3rd degree heart block. I now have a pacemaker but I pace about 1% of the time. I have thyroid disease as well. I have irritable bowel, panic attacks and anxiety. I was diagnosed today with inappropriate sinus tachycardia. My gut is saying they are all related...but I can't figure out how and neither can my doctor.

When I take the thyroid dose I am supposed to (88 Levoxyl)-I go into tachycardia. It's like poisen in my veins...I get shaky, panicky...like I am being overmedicated. When my dose is lowered (75 Levoxyl) I am clinically hypothyroid. If I take the higher dose my EP wants me on a beta blocker. But that lowers my blood pressure so much I get dizzy...then a panic attack because I am scared to death.

I tracked myself on the lower dose for 1 month. All tachycardia could be explained and deemed appropriate. Meaing- RHR in the 140's while I was at the gym would make sense. So they took me off the beta blocker.

I have no physical symptoms of hypothyroid. But EVERY symptom of hyper. Can the test results lie? What could be causing me to be so out of whack?

I am taking Xanax currently to block the panic....knock on wood been good for 2 weeks. I feel like my body just "runs" faster than other peoples. Inability to gain weight, can never sit still, always on the go.

Would could make someones body besides their thyroid just run too fast? My father died at the age of 50 from a sudden heart attack....so I am eager to get to the bottom of this.

I found a site that talked about ITS and dysautomania. I felt like it was talking about me. Does anyone have any advise or experience with any of the above?

I feel hopeless. I have a beautiful baby and I am so worried about the above that I am missing precious time with her.

Please help....thank you