Website for fibromyalgia friendly diets?

My partner has terrible fibro. I have always been a (relatively) good eater (ie, lots of veggies and protein) and he has improved considerably since we have been together. The other day he suffered a set back which I suspect had to do with disgusing canned meatballs he ate, against my advice. I highly suspect that his condition could be improved on a diet that eliminated preservatives.

Anyone know of websites that could possibly affirm this and provide help and/or recepies?

He's not so sure it would help and cannot work right now so is worried about the increased cost so it would help if I could sway him.