My father in law (>65 age) is having pain in leg from waist to the toe. It’s not on any joints but he says he feels it inside the bones. What specialist can we consult? Available in fourways area?

GP. You can visit your GP to do examinations, xrays, sonar, blood tests or whatever is needed to make a diagnosis. Then your GP will be able to treat you or refer you to the proper specialist to solve your problem. .
Many possibilities. First would see PCP. This may be something that a neurologist, rheumatologist or a neurosurgeon/orthopedist, oncologist may need to see depending on what the root of the pain is. So best to see his primary care first.