This is a simple technique that can help with low back, sacroiliac, and hip pain.
As you are lying in bed, hike one hip toward your shoulder, then lower that hip and hike the other hip. Do this up to 50 times.
Stop if this causes or aggravates any pain.
This engages the quadratus lumborum muscles on both sides and helps to mobilize the sacroiliac joints and lower back.