I was mis-diagnosed in August. They mistook my ulcers for just an extremely hungover and dehydrated college kid.
But I feel you on the feeling like death thing. I hadn't eaten in about 5 days and couldn't keep anything down, water, whatever. The only thing I did in the bathroom was puke up stomach acid. Every time my body made more, I puked it up. Usually about twice during the night and countless times during the day.
The Saturday afternoon before I went to the hospital I remember forcing myself to get dressed and go downstairs where my friends were because I was scared if I passed out I wouldn't wake up. Finally when my friend checked on me at 3am I went from dead asleep to puking up acid, he had had enough and literally carried me to the car and drove me to the hospital. They gave me about 5 or 6 IV bags and some morphine. I walked out fine. Next day I was back at square one and wound up going home to see a competent doctor who knew the problem right away.