Can you please help me solve this pain?

I have a thyroid condition (low), fibromyalgia, osteoarthritis (very thin bones), depression, anxiety, and I also have this chronic pain in the tailbone area. I have been through MRI'S. CT's, nuculer medicine x-rays, and these tests come out normal other than showing the arthritis.The coccyx area hurts so bad when I sit down, and when I start to stand up and the pressure is released it is almost unbearable.It is starting to hurt when I lay down and stretch my legs straight out and it even feels swollen the that area. I have had this pain for over a year but it is really to a point now that I do not know how much longer I can go on. I do take pain meds but it does not take the pain away, and I do not want to continue meds, I need to know what the cause is for the pain.  What could be causing this horrible pain, it has changed my whole life! I understood that when the Dr's ordered the tests it was to look for a couple of things, well I do not understand why the Dr's do not order a complete test on looking for anything that could cause this chronic pain!! My important question If I may ask, can medical conditions not always show up on mri's etc? HELP PLEASE!

[Dr Rajgopal]

Hi,
There are many causes of tailbone pain including Sciatica, infection, pilonidal cysts, Tarlov/meningeal cyst, fractured bone, Unstable or dislocating coccyx, Spur on coccyx, Misaligned, rigid, or long coccyx, Muscle spasm or tightness, Pudendal neuropathy, Cancer, Neuropathic pain, Previous medical procedures, Deposits of calcium in joints and Idiopathic coccydynia. The usual tests done to diagnoses the cause are CT scan or MRI. As the MRIs in your case are inconclusive, the cause could be an infection. Please check with a neurologist for same. Another cause could be dislocation of the coccyx while sitting. A dynamic (sit/stand) x-ray or MRI scan may show whether the coccyx dislocates when the patient sits.  Sometimes there is no cause of the pain and is termed as Idiopathic.  
Rest,  anti inflammatory and pain medications can relieve symptoms. Some patients with chronic coccydynia are treated with local cortisone injection. This injection is performed in the doctor's clinic and can relieve the pain to a great extent and may even relieve the symptoms.Rarely, when patients have persistent pain, a surgical resection of the coccyx can be performed to remove the irritated bony prominence.
Since sitting on the affected area may aggravate the condition, a cushion with a cutout at the back under the coccyx is recommended. Please consult a neurologist for the management of the pain. Hope this helps you. Take care and regards!