I have bad lower back pain when i lie down, as well as constant bilateral lower leg pain. i'm 22 otherwise healthy. any thought?

See below: Go see an orthopedic surgeon and get a xray of your back. Lumbar spine good luck thank you.

Uncommon: Having severe back pain, especially when laying down, is uncommon at your age. Constant leg pain is also uncommon. Medical evaluation is necessary to elucidate the reason for your symptoms.

Back Pain: I would be most concerned about nerve compromise inside the spinal column. This could arise from disc disease or a bone spur, but other possibilities do exist. The fact that lying down makes it worse suggests that the spinal column is the most likely source for the symptoms. I suggest you see a back specialists for proper evaluation and treatment.

See your doctor: With rhe leg and back pain it could be a pinched nerve or other problem so see your doctor.

Leg pain: Is likely from the back problems. Mri would be needed and consult with orthopedic surgeon or pain management.

Lower Back Pain: Pain in the back and legs in a horizontal position that is not relieved by changing position except to be upright is a red flag. Concern is something blocking venous return of blood through batson's plexus. Especially concerning if radiating into legs.