Afib, PACs, Sinus Tachardia, new episodes, help!

[Karynecpa]

Please help.  I have had a history of sinus tachicardia since my 20's (off and on).  Then in 2012, I had an episode of SVT that was taken care of in the hospital followed by an ablation.  No SVT since. But since then, I still get some sinus tach episodes especially at night and some skipped beats.  I have had a few episodes where I it lasted for a few minutes and that was a terrible feeling.  This past Thursday, right before I was getting ready to leave for work, my heart was feeling like a jumping bean, very erratic, and wouldn't stop,  I have an app that does an EKG and it said PVC with attrial couplets. i went to the ER right after and they were picking up only PACs for the 3 hours I was there, blood work was fine so they discharged me.  Then it happened again last night (the next day from the last episode).  Same EKG reading results but this time, was in sinus tachycardia too.  I told myself to wait it out, I drank a big glass of tomato juice, started to get the shakes, and then calmed down. EKG was normal 30 minutes later.  I have an appointment with an EP next Tuesday and am getting a monitor but what can I do to prevent these attacks?  They are just awful and very scary. And I don't want to run to the ER unnecessarily again. But when I'm in the episode I feel like I'm dying,  I am 48 year old female with a history of thyroid cancer and take nature-throid.  My thyroid levels are low normal but I called my Endo and asked to reduce them just in case it was aggravating my heart.  Someone please help me.  Any words of wisdom or ideas how to prevent this from happening again? Thank you

[Karynecpa]

Not sure how to edit my question above but I also take Metroprolol 25 mg ER (split in half twice a day) and Propranolol 50 mg at night.  The Propranolol was added about 8 weeks ago when I was complaining of the high heart rate at night plus higher blood pressure.