Have you had any changes to typical day activities?
The TFL attaches on the side of the iliac crest. Multiple abdominal& back muscles attach to the iliac crest.
Pain could be due to irritation of the TFL.
One hip may droop when you run putting stress on the muscles at the side of the pelvis.
May need to work on hip and ab strength to correct the hip from drooping when running.
A couple to start with:
Wednesday, November 22nd, 2017 – TFL, Hip Extension & Back Pain
Tuesday, April 10th, 2018 – Anterior Hip Prep
Let us know how things progress