Just Started With Attacks Out of the Blue When Ever I Take My Oxycodone

On friday the 28th of january, I got my refills of my oxycodone. I have been on them for 3 years now and now at a dose of 100 mg/4hr since i was diagnosed with ALS. Everything was fine until I picked up my m,eds 100mg every 4 hrs. Shortly after taking it, I started to feel my heart do crazy beats and fluttering, my face gets really hot, my hands get ice cold as do my feet and my face gets extremely hot. I have never had this happen before and I thought i was having a heart attach I was rushed to the hospital and it turned out my heart was fine, when i got home, i went and took my medication and lo and behold within 15 minutes of taking them, it started so i thought there was a contaminant in my medication, seeing now there is but can someone tell me why this started so suddenly??? I have one theory, about a month go I had a really bad week and during that time, I took valium for the extreme muscle spasms and when i got better I stopped taking the valium and continued back with my own normal meds with out valium, for several days and I didn't have any problems at all could that be why they started happening?did that make this happen?? Further more, the day it started was when i had picked up a refill and took from a brand new bottle, I took the dose and there was my FIRST PANIC ATTACK. i DO NOT HAVE ANY HISTORY OF ANY ANXIETY DISORDERS AT ALL!