How do you know if your ailment is psychosomatic or real?

Real vs. Imagined? "psychosomatic" means only that the mind and body influence each other -- not that illnesses aren't real. These are physical disorders in which both emotions and thought patterns seem to play a central role, and often develop when a person's disease-fighting ability is weakened from stress. After losing a spouse for instance, one could become hypertensive, have a heart attack, get ulcers, etc.
Ask the doc. If your doctor can tell you what is real about the illness then it's good. Get an opinion from a university or major medical center.