Can intestinal candidiasis cause recurrent vaginal yeast infections and abnormal/painful/irregular bowel movements?

I suppose : Once you have it in the GI tract you could have it vaginally as well. Simple siggestion: see your obgyn and the final response will be yours in no time.

Yes: You need anti candida diet: no sugar, no flour products. Until you get better, also no fruit and no carbohydrates. Eat 1 tbsp of coconut oil with each meal. Eat lots of non starchy vegetables and enough quality protein. Consider betaine hcl with each meal, take it in the middle of the meal. Also take saccharomyces boulardi, which is the yeast against yeast.