I've been anorexic AND obese for years. Negative for thyroid disease, and cushings, and diabetes. Any ideas?

I was 5"11" in high school with 32C 27 34 figure. 135 pounds was still a size 13 (33 mens). I was thin, but wide, so I looked fat, with tight clothes on, but you could see my ribs. 5 days a week I ate a turkey sandwich, milk or chocolate milk, or I'd just have a frozen yogurt. and then 4 hours later maybe I'd eat two cookies. On weekends I'd eat a basket of fries on Saturday. I did not eat on Sunday. My hair started falling out really bad, but my nails were healthy. When I got to college I was so afraid of the freshman 15. Instead I gained 85 pounds in 3-6 months. I ate 4 times a week. sometimes ramen. Usually salad and soup. Drank coffee, and worked out with the rugby team. I had 5 kidney infections in one month. Carbs in the blood, did not drink alcohol. At 220 I joined a fat boot camp. If you didn't lose weight you worked harder and didn't eat. I didn't eat usually for 4 or 5 days straight. I worked out 12.5 hours a day, rocky style, with pushups with weights, punching with weights, aerobics with weights, lifting weights while running up stairs, situps and pushups for mistakes and lots and lots of running. After 3 months I hadn't lost a single pound. Tried every diet known to man. Tried every calorie intake from 2000 to 275. Regular exercise. A few years later mysteriously I lost most of the pounds in 6 months on the pizza and vodka diet, didn't change anything but went from 220 to 180 in 4 months. Then I ballooned from 180 to 280 in 3 months and still hadn't changed anything. The weight tore my skin open. I stopped eating for weeks at a time. Now I am still at 280-285. I work out 4 times a week, do fencing 2x a week, soccer 2x a week, softball several times a week, and go out dancing 4 times a week. My knees are giving out, and I have infected cysts and boils under my skin, my muscles are thinning, my skin is thinning, and a hissing noise seems to come out of the back of my neck. My arm tore open at the pit while lifting weights. Still no muscle, it's all fat and hardly any muscle except for my calves. I eat approximately 550 to 1000 calories a day. Depending on liquids. 550 in solids. Proteins, usually in the form of low carb fiber bars, low sugar veggies, and flax and olive oils.