Gamunex headaches

I have been on weekly IVIG every 10 days for about 4 years. About 18 months ago they switched to Gamunex and I have headaches that are dibilatating that sometimes are constant until the next treatment.They treat it with pain meds.I have other side effects but they very from each infusion. I would like to know if anyone has had this with Gamunex. Thank you.