Yikes, that sounds awful. I hope you get to feeling better quickly.
I remember that Butterflake had some similar reactions to her IVIg - sick for 2-3 days, throwing up, diarrhea, chills, but I don't think she had the headache you describe.
Do you ever have issues with migraines? Could the IVIg have kicked off a migraine response of some sort?
Sure hope your Dr has some options to keep your next infusion from being so traumatic.
Lynnwood, Lupus & Sjogren's Moderator, Dx: 2000DIAGNOSING LUPUS & HW's LUPUS 101
"Life is far too important to be taken seriously." - Oscar Wilde