I have worsening pain betw hip and spine only on 1 side. Achy into front on leg and knee pain on same side. Suggestions & type of dr to see?

Need evaluation. There are many different possibilities as to the source of the pain. It could be due to a pinched nerve from the lumbar spine, sacroiliac joint dysfunction, hip disorder , muscle strain, or many other causes. Discuss first with your primary care physician to initiate the work up (physical exam/xrays ) and if the pain persists/progresses a referral to a spine specialist may be necessary.
Spine Physiatrist. A physiatrist is a doctor trained in the evaluation and treatment of musculoskeletal problems. He will be able to tell if your problem is related to nerve pinching, skeletal abnormality or muscle spasm.