Hello~First, I am wondering if you have thought of seeing a chiropractor for your numbness and pain, they specialize in these areas. They will first take an x-ray, study it, then go over the results with you. Normally, after a few treatments, folks start to feel better. When you return home from your travels, this might be worth looking in to.
As to the blood test showing any links to cancer, some can, but it is usually very vague, I know there are special blood tests for cancer as well as bone biopsy's if you are concerned over bone cancer. Some x-rays, CT scans and MRI's can show cancer as well.
My best advice would be to see your chiro when you get home, ask him/her these concerns. They will always be glad to refer if they think yours in not a chiro case. Also, ask your doctor about the chance of blood work showing cancer cells and a possible bone biopsy.
In the meantime, start taking Vitamin D3, this is good for bone health and in many cases can help with some of that pain, also take a good, high potency multi-mineral and "B" complex, theses, too, should help, plus make you healthier in general.