you cant address these two issues at the same time. If you guess around it will drive you nuts.
As long as you dont have prove that you have candida you should not only assume you have it. If you have an IBS with constipation than the high fibre diet here fighting against candida will be good for you.
So dont worry about that. If you have an IBS type overflow IBS, that is high speed of digestion and diarrhoea, you should NOT follow this diet as it is high in fiber which will irritate your guts more giving you more diarrhoea.
Check first if you have IBS and heal yourself. I found IBS the essential guide from Professor John Hunter a great book. There you can find out which type of IBS you have.
If you have constipation type of IBS you can safly do the diet here as it is high in fiber and in this case will only help you. You see there are different types of IBS.
If you suffer like most IBS folks from stress and anxiety. You should test EFT from Gary Craig. Its free on-line and helped me a lot.
hope that helps