Might be a bit late to this.
When I was in 4th grade I suddenly stopped being able to keep food and water down. I puked as soon as I swallowed anything. I tell my mom and I'm ignored. A week later I begin to feel the effects of dehydration and malnutrition. I couldn't get out of bed. My back hurt so bad. All I could do was cry and moan in pain. My mom would yell at me to keep quiet every day and be especially threatening when parent showed up to our house to pick up their children, as my mom ran a daycare.
At this point my sense of time was totally screwed. I want to say this went on for another week but realistically it had to have been just a couple more days. So one day my mom grabs my older brother, younger sister, and I and we go to a hotel. She did this periodically to show my father that she could take us and leave whenever she wanted. Well at this point I was dry heaving and retching near constantly. The pain in your abs and lower back after puking constantly for a week and a half is something special. I remember being screamed at by my mom because I was ruining the 'vacation' for them when I started blacking out.
I wake up and I'm in my dad's car headed to the hospital. When we get to the emergency room the doctor can't find my veins. Something about the dehydration. I black out again. Wake up in my own hospital room with I.V.'s in me. They had me on some child's pain killer- sera or sero something and loading me up with saline solution as quick as I could take it.
Four days later the absolutely could not figure out what was wrong with me. I still wasn't eating. Whenever I wasn't sedated until sleep I was dry heaving. God the fucking pain. I had to drink irradiated ink so they could see how my digestive system was functioning. It tastes about as good as you'd think. I couldn't keep it down long enough for it to enter my digestive tract so I had to keep drinking it over and over until it did. Good times.
Eventually I'm told I'm going to be moved to a university hospital where they'll do exploratory surgery on me. Before that happened I ended up eating some toast and keeping it down. A doctor finally diagnosed me with Cyclical Vomiting Syndrome. After one more resurgence about a year later it was never an issue again.
I'm 24 now and I've been through some pain and broken some bones but I'm fairly confident that nothing will ever hurt as bad as those 3 weeks.