A friend of mine had a weeping appendix. It started when she was 14 and has been the bane of her life since (she's late twenties now). When it first flared up, she was taken to hospital with what she described as severe abdominal pains. They had subsided within thirty minutes or so and the incident passed without further investigation.
Every few months, though, she would get the same symptoms, sometimes resulting in her being left incapable. I shared a house with her for a couple of years and it was an entirely unpleasant experience to witness her curled up in agony on the bathroom floor, screaming for an early death. She underwent countless tests (although, incredibly, not one for appendicitis), with doctors unable to find a cause. The point came where they actually decided that she was making it up in order to gain attention. She is a highly intelligent person with, shall we say, artistic temperament, and her eccentricities were considered above what, to her, were very real physical symptoms; but because doctors were unable to find a physical cause, they gave a psychological diagnosis.
For the next seven years, she went from being prescribed anti-depressants to anti-psychotics and spent several periods in psychiatric care. Her medical records and the 'professionals' who worked on her case were adamant that her pain was in fact psychosis and every incident was used to justify their diagnosis.
Eventually, after roughly seven years of being disbelieved, and of desperately trying to convince people that she was enduring these episodes of extreme pain, she had one which was prolonged enough for a (new) doctor to examine her appendix. I may remember this incorrectly, but the gist is that he discovered inflammation and scar tissue which showed that the organ had been swelling and then rupturing, then healing; only to repeat the same process randomly throughout her life. The describes the relief at this diagnosis as being one of the most intense experiences of her life. Seven or eight years on, and she's still dealing with the 'help' she received for her mental health problems. No more gut ache, though.