What are causes of sacroiliac pain?

Pelvic imbalance: Sacroiliac joint is the most complex joint in the spine. It moves in six planes of motion and is l shaped. Has innervation from the back and in the front. It can become misaligned and cause a lot of pain due to abnormal friction of ilium on sacrum. In someone young like you it is usually due to pelvic imbalance from short leg syndrome or psoas muscle spasm.

Varies: 1) sacroiliitis from seronegative spondyloarthropathy. See a rheumatologist 2) arthritis: a steroid injection into the lower joint by an interventional spine specialist. Radiofrequency ablation can cause much longer relief. 3) lax ligament or pelvic imbalances or uneven leg length.