Had injection 2 pm today immediately had head spins like I was of...

I ave been getting the cortisone shots on and off for about a year now, basically, whenever my ankle flares up. I had one earlier today (or yesterday as it may be), and now here I am at 2:45 am, deathly tired, but with my mind so active I cannot sleep. I noticed the same thing after an injection a couple of weeks ago. I can't believe I never noticed it before. I have always had the woozy/loopy feeling afterward, afraid to drive home, but thankful I live less than a mile from the docto's office. This is usually followed by a day of nausea and other side effects. It's weird, though. The websites with info on this drug don't talk about the nausea, the dizziness, the "feeling out of it", the headaches. Only that the pain is worse before it is better (definitely true!). But do the docs not know about this or are they just turning a blind eye? I keep reading that such side effects aren't possible because cortisone occurs naturally in the body. But the stuff they are injecting us with is not produced by ur bodies. It is synthetic, and eing that we are not producing the dose natrally, it is very lkely overload. So, how can there not be side effects?