Headache after CT scan with contrast - normal?

[Cockadoodledooo]

I had a CT done this afternoon (chest/abdomen) using contrast (didn't remember to ask what and the letter doesn't say). Scan finished about 1.5 hours ago and now I have a raging headache. I had the same procedure 3 months ago and felt completely fine afterwards (same hospital, same bit of me scanned so guessing same contrast medium used).

I've googled but only seem to be picking up results relating to scans of heads, where presumably the headache is the cause of the scan rather than vice versa..

I've drunk 1 litre of water and 500ml of fizzy drink since the scan.

Can anyone reassure me that this is normal please?!