Randomly my heart rate shot to 140+ bpm and i was just sitting still... after 2 hours its still beting in the high 90s to low 100s. my resting is normally 85ish. I have hypothyroidism that has recently switch to hyper with no apparent reason.. I also have anxiety.. but this wasnt an anxiety attack, i was not anxious at all or anything. but nothing would slow it down and it started feeling like it was hammering in my chest. any suggestions? im taking levothyroxine 100mcg and zoloft 25mg