How can I get rid of Jock Itch / Tinea Cruris / Ringworm?

Have you been checked for diabetes? Fungal infections are difficult to treat in diabetics. I would consult the dermatologist again, you may need a longer course of treatment with fluconazole. Also avoid foods made with white flour, white sugar and alcoholic beverages because these all encourage and feed fungi so avoid consuming them for at least 6 months to a year then you can try to gradually re-introduce-if infection re-occurs you may have to avoid them permanently. You may want to also try taking probiotics (Culturelle is a good one but any acidophillus and lactobacillus product with live cultures is good) to balance the "good" bacteria and drive out the fungi. You probably have systemic fungal infection and this is making you prone to outbreaks on the skin. Have you tried getting powdered boric acid, mix the powder (use about a half teaspoon) with unscented lotion or skin creme (about a half ounce with that 1/2 teaspoon of powder) to form a paste and apply it to the area at night and rinse in the AM. It may help to kill the fungus. DO NOT take boric acid internally though! It is deadly poisonous to take it internally. ONLY use externally. Dont apply any cortisone to the area either because this fungi loves cortisone and it will make the infection worse! You can also use Lotrimen cream or any OTC antifungal during the day after cleaning of the boric acid paste. Good luck! This is a pain, I know! I have had trouble with Candida most of my life and some people like us are just prone to overgrowth for some reason-usually because our body pH is such that it encourages the growth. You can try foods to bring your body to being more acidic like consuming apple cider vinegar daily.