Candida is a yeast infection and I've never really noticed any overlap between it and Crohn's, but that's been my experience with it. Generally your GP can give you an anti-fungal pill to clear candida up. It's usually brought on by taking antibiotics (especially if you're on immunosuppressants). It's something you should go to your GP for more likely than your GI, though.
From my experience, candida is usually associated with cottage cheese-like discharge, smell, vaginal itching, etc. Crohn's is usually more diarrhea, abdominal cramping, blood/mucous in stool, and so on.