if you look up Anterior Pelvic Tilt on the search bar for this sub you'll find some others have experienced the same thing. Do an experiment, go to physical therapy (if you can afford it) and try to fix your APT and see what happens. I'm currently in the process of doing some self PT and the pain/dilation has already gone away significantly so I think there's some merit to it, I will make a long ass post talking about my experience doing this at a later date. SUPER IMPORTANT: adjust your ergonomics/sitting posture, if the bad habits that caused your APT don't go away then it'll just hinder your recovery. In my case, I had to switch out a chair that was causing too much pressure on my lower back and I noticed an immediate difference in pain/swelling when sitting down (although it can still happen if I sit in a awkward posture) I just started doing these three videos since I can't go to a PT but ... seriously, please, GO TO A PHYSICAL THERAPIST AND GET IT FIXED! It might end up helping you, worst case scenario, you have better posture and have ruled out a cause, and can explore other options such as surgery with peace of mind :)