Could an injection for a heart test have have caused this Vasculitis - Giant Cell? I never hot burning sensations and head pain 2r hrs/day before this test. Someone please tell me if this is possible and what could have gone wrong.

I have just discovered that this  can be walking on the treadmill one day with an IV injection and a scan of my heart latter. The next day I had the same scan but was injected with substance and told to eat lunch and return after one hour. On the second day immediately after the injection as I was walking down the hall to go for lunch my head felt like it was on fire. I was alarmed but did not tell anyone. When I came back for the heart scan( the same test I had on day one after the treadmill) I was very anxious, infact I had panic attacks as they raised me up towards the scanner. I couldn't figure out why I was reacting the way I was, even the nurses were surprised because the previous day I was fine. That evening I had horrifble, bizare nighmares and work up in the morning with a headache that lasted all day, and everyday for 21 days. To this day I still have terrible head pain and pain in my eyes. Its been over a year.
I was diagnoised with Giant Cell last April and treated with high dose of predisone since them.
I can't help thinking that whatever was injected in me the 2nd day is the reason that I am in such pain in my head.Out of the blue I get a severe head pain for 21 days, 24hrs a day. What was I given and how do I find out? I can't get past the nurse when I ask this question from  nurse in the dept that  I had these tests done.I asked what was in the injection and she sort of chuckes and says I double if you'll be able to find out.
How could someone that never had headaches become become seriously ill after a test? I feel that something went wrong? What was I injected with? Please help me because I don't seem to be getting better and I'm not sure if the predisone is a good idea. I've been told I have Giant Cell Arteritis.
I am very sensitive to medications and toxins in the air. I get weak and dizzy if I'm around computors and equipment like zerox machines.
How do I get the hospital to investigate what they gave me on the 2nd day. Why was it injected differently?