Look into candida, Could be that you have this especially if it keeps coming back. Try a candida diet, Anything high in sugar feeds it so cutting out all sources of sugar and taking keffir supplements that boots do an own brand of plus natural yoghurt and a prebiotic. If you are already doing as others have advised with not using scented bath products then it may be a overgrowth of candida. It's a real hassle to have to not work due to Thrush, For me it's Coldsores which puts a spanner in the works.