I do not have tail bone pain,but I did have a similar doctor experiance.In January of 05 I began to have numbess in the right side of my face while on a bike ride. I rode home and my family took me to the E.R. They found nothing. After several neuroligist, 2 CT scans,6 MRI's, and countless blood tests,there was nothing. They looked for everything MS,Lyme dissease, vitiman B deficiantcy, cancer, allergies, it was the scariest time in my life. Tests always came back negative and I was repeatedly told it was stress go home and relax.
By Febuary of 08 it was all the way down the right side of my body. I was sluring my speach and loosing control of my right leg from time to time. I went to yet another neurologist and was perscribeded a catch all drug that they give to everyone when they don't know what else to do.
I began to look for a job I could work from home and chose one that promoted green products. The company askes that you are a customer so you can really talk about the products. 3 months later I had no symptoms. I went to my doctor and told him what happened. He said It had to have been an "external toxin poisoning".
There is no test to look for this and it is not a widely accepted diagnosis. They only way to know if you are being negatively effected by household chemicals is to get them out of you house completly. If I hadn't stumbled onto my diagnosis there is no telling where I'd be.
So go to the doctor and do not give up! They are human beings just like us and do not have all the answers, so if one doesn't know try another, and keep researching new info is coming out all the time. If you find something to try and it is not harmful, try it even if it seems crazy.
I would have never guessed my make-up, cleaning products, etc... were making me so sick, but neither did my 9 doctors.
Good Luck,
L.