First, I just want to tell you to try not to worry so much. I know that you are going through a very rough time right now, many of the people on this board had to wait several years to get the proper diagnosis, and many of us have had our symptoms dismissed as stress-related or 'all in our head.' What you are going through is very difficult, but you are not alone, there are plenty of people here who can sympathize with you. It is scary to know that you are sick and not have a diagnosis, but just remember that even if you do have something serious like MS or fibromyalgia, these illnesses are not likely to kill you anytime soon.
My advice to you is to be persistent with your visits to the doctor, and keep looking around until you find someone who is willing to take you seriously. At the same time, try to be patient with the doctors. A lot of these illnesses are difficult to diagnose, and some can only be diagnosed after all other possibilities are ruled out. This may mean playing along and letting them run tests/try treatments until they can rule everything out.
You may want to try to get an appointment with a rheumotologist first instead of a neuro. Rheumatoid arthritis or fibromyalgia could be the cause of your symptoms, in which case a rheumotologist would be more knowledgable than a neurologist. Also, just FYI-IBS is often linked to autoimmune disorders; my mother has fibromyalgia and IBS, and I have MS and IBS.
Good luck. I hope you get things figured out soon.
Be joyful in hope, patient in affliction, faithful in prayer (Romans 12:12).