The contrast always seems to give me just a slight burning sensation all over for a few minutes after it goes in, but seems to go away quickly. I can sympathize on the spinal tap. Mine took multiple attempts by two different docs over the course of two days. The first doc couldn't get the needle in because my back muscles kept spasming and locking up the needle. I think I about broke my wife's fingers squeezing her hand a few times. She finally gave up and we had to leave and come back the next day to try again. That doc got it in on the first attempt and it was relatively painless.

Good luck with your results and congrats on surviving the tests!