welcome to health care magic!
After reading your question I feel that rather than having some eating disorder
you are having severe gastritis
, may be some ulcer in stomach / duodenum
, because of which you feel pain after eating food and if you don't eat, there is accumulation of acid, further aggravating the pain. Due to pain, you can't eat enough and there by a viscous circle is formed.
I have seen such cases respond very good to a course of antacids with antibiotics to kill the bacterial responsible for increased acid production. It is not a serious condition but certainly painful.
You should see a doctor and if I had been treating you, I would go for ultrasound
abdomen and blood counts just to have a safe hand and negate any other cause and give medicines.
Along with this you must keep a check on what and how much you eat.
I would prefer my pt. should take small and frequent meals, to take more of salad and curd. It would really help if you avoid spicy, oily and hot foods for some time and go for bland food.
Avoid tea, coffee and increase your liquid consumption.
With treatment I'm sure you will become all right in few days.
Hope this will help you.
feel free to ask more regarding this.
Dr. Manisha Gopal