The Pharmacy Recently Switched The Manufacturer On My Generic Levothroxine

The pharmacy recently switched the manufacturer on my generic Levothroxine 137mg. It is now Sandoz. I started experiencing almost heart attack like symptoms ( tightness in chest, heart feels like it is fluttering and this comes and goes about every 30-45 min., sweating & elevated blood pressure). I actually went to ER because I thought I was having a heart attack. Test showed my heart was fine, but BP was 180/110 and my normal is 125-130/75. So, I quit taking it and my BP & HR returned to normal after 1 1/2 days? Have you heard of this being a problem?