Sudden onset dizziness

I haven’t had a crisis in 15-20 years. Yesterday I had a full blown one-nearly. I became very dizzy-had to have help walking. Not sure why-but perhaps sinus related? I took 5mgs of cortef, laid down for a while and then started vomiting. When this was over I had my son crush a cortisone tablet and mix it with water-I was able to slowly sip this solution and keep it down for the most part. The nausea subsided but I was terribly weak and still a bit dizzy. Did the crushed pill again and kept it all down. Recovered enough to get to the car (two flights of stairs and a walk) with the help of my sons, and then to the ER. My question is-I can’t come up with anything really that led to the crisis! They found nothing at the ER. They did follow my direction and gave me a dose of cortisone and a bag of IV fluids. I’m much better today but am worried about the sudden onset. And, yes , I will get some injections. I’ve thrown so many away over the years that it seems a waste of scarce resources