Nitroglycerin and low blood pressure

I got nauseous and my heart stopped soon after being given a nitro tablet under my tongue. I was revived with oxygen after about 20-25 seconds. I had entered the ER with a fever and chest pains which turned out to be pneumonia. My heart was completely check out with the plumbing and electrical found to be perfect. They even gave me more nitro during the electrical test with no effect. After waking up from from the elect/nitro test my heart went into a-fib on it's own. The only previous heart problems I have had were a few short a-fib episodes over the last few years.Here is what I think: My skin is always very flushed and with the fever my capillaries may have already been open when given the nitro causing extra low blood pressure. The latter negative nitro test was done in a cold room but when taken up to my regular warm room lying on a plastic mattress my capillaries opened and the residual nitro from the test kicked my heart to a-fib.