Suggest Treatment For Sinus Tachycardia

I am a 36 year old female. I have inappropriate sinus tachycardia. About 2 months ago I got a rash, it was diagnosed as a bacteria infection. It later seemed to turn into hives (I realize that makes no sense I am simply telling you what the dr told me). I was covered head to toe in hives for a month, some drs said it was possibly vasculitis, while eventually a skin dr told me it was hives he was sure. I never felt....right since. All of the sudden in the past 2 weeks I have developed severe anxiety and shortness of breathe. I was given a ECG and just found out that the T waves are abnormal. I have had such a HUGE mix of issues that some how all seem unrelated and yet, I am sure some of them are. I have no allergies except codeine and I never touched it. I still do get blotches of a rash/hives. I am scheduled to see an immunologist, but not until august. I can not catch my breathe and this anxiety is...well makes NO sense. I am seriously frustrated and just want to feel normal. I will say I get the odd day where I feel perfect.