5 STARS UNITED Knee Pillow for Side Sleepers - Hip Pain Relief, Memory Foam Leg Cushion for Side Sleeping - Between Legs Pillow for Sciatica & Lower Back Pain, White

Might not be the mattress. I use a knee pillow such as this: https://a.co/d/09mE3p2i It aligns my legs and presents hip and back pain. I have a foam one for home and an inflatable one for camping and travel.