The 2 red Xs mark roughly where your sacroiliac joints are. If you have pain at either of these points, it may be because your glutes are weak or not firing correctly during your gait cycle. The glutes are a vital part of giving stability to these joints. So, if you sit quite an amount, your glutes are probably asleep much of the day and/or possibly weak.
What can you do:
First, find out the cause and know if the following is right for you; if so…
Second, strengthen the glutes, e.g. glute bridges.
Third, stretch the opposite side, i.e. iliopsoas.
Why stretch the iliopsoas? That’ll be in the next post.