Root Canals Causing Migraines??

Hi,

My husband has always struggled with migraines every once in awhile. Lately he has been getting several a week. Just about every tooth has either a root canal or a filling. I am trying to find info. on whether or not this could have caused his migraines to worsen, by some bacteria etc. Does anyone have any info on this and does it cost a lot of money to have this corrected?

Thanks
Wendy26