I Had A Cortisone Shot In My Knee Last Wednesday.

I had a cortisone shot in my knee last Wednesday. After the shot, though my knee was better, I got a headache that lasted approximately 36 hours. Have never had a headache like that before. Also, my face flushed (red).
You should know that prior to my shot I had not slept for 24 hours (had nothing to do with shot.... I do lead a very stressful life) I could not sleep the night of the shot because of the headache. I also took around 9 headache powders over 24 hours once the headache began. Any idea what happened???