Okay what you will need to do is lie flat on the floor on your back, put that icebag right on the painful sacroiliac joint lying on it.
Next as you are flat, guide your partner to find your inguinal ligament ofn the right first. Once they kow where it is have them remove their hands.
Slowly bring your knee to your chest, then have your partner pin that inguinal ligament again, while your knee is ast your chest.
After this very slowly straighten your leg out. See how far it can go without too much discomfort. After this hold the position at where there is some slight pulling. This should not be extremely painful, a little discomfort is okay.
Once you've held that position for about 30 seconds, go back to both of your legs being flat on the ground.
Repeat the steps 3 to 6 more times for each side of your body. This helps immensely!
Next, hang on to something stationery and sturdy such as a door frame while lying flat, and have your partner gently put the back of your knees in the crook of their elbow.
Have your partner gently pull your legs toward your feet for 30 seconds at a time, when you feel a slight sacral stretch, that's where to hold for 30 seconds, again do this three to six times, and keep that ice pack on it.
Hope this helps you out, and offers a little relief! chronic pain is no fun!
Andrea