This came on rather suddenly and is not due to exercise. Both my lower back and legs ache when I lie down. It is not a muscle cramp, or sore -- it's a constant ache. It is relieved by sitting and walking, but returns when I lie down. I am a 67 year-old male and am taking no medications.
Sounds suspicously like neurogenic claudication (unhappy nerves usually from a spinal problem), as oppossed to vascular claudication which gets worse with walking. Neurogenic claudication usually improves with sitting because this body position relieves pressure on the nerves.
So, why are your nerves suddenly unhappy? That's for you and your doctor to find out.
Dr. Christina Lasich, MD
Sounds like a problem with your lumbar spine and sacroiliac region, most likely caused by stenosis, herniated or ruptured disc, or similar abnormality that is pressing on the nerves supplying the lower back and legs. This is important to find out, both to ease the pain, but most importantly because at your age there is also a possibility of an embollism or blood clot in the legs that would need to be addressed immediately. I am not a doctor, just have my own spinal problems and a family history on them as well.