What you have described to me sounds exactly like SPD. The top of my legs/groin ache constantly. There are different severities of it, not everyone would necessarily get shooting pains in their pelvis surely. Im not a doctor but I am an expert on this condition, Ive lived with it for 2 years now and I know that if someone hasn't been through it themselves they have no idea how it feels or what to look for.
Unfortunately I do not know of a cure. Physio may help you, have you tried? People tell me to try Chiro but Im too afraid. If the thought makes me feel nauseous I know to stay away!
I was diagnosed by my physio coz I guess I fit all the symptoms: Couldn't roll in bed, couldn't lift 1 leg higher than the other etc although I could touch my toes after pregnancy with much more ease than I could when I was a dancer 10 years ago! Go figure! I have too much relaxin in my system!
By the time I went to physio at 6 months pregnant I had left it too long and the worst of the damage was done, she said. I wore a belt which helped a lot and it became almost a security blanket for me.
I told my obst and midwife about my condition but wasn't taken too seriously (not many people will) so when I gave birth I had 2 people pushing against each leg and me pushing against them (all that pressure meeting at my pelvis) and I'd had an epidural so I had no idea of the damage I was doing. Plus I just wanted to get my little boy out as quickly as possible as his heart rate had gone a little erratic and I was frightened.
I continued to wear my brace after that and only went back to physio a few times (its hard with a new baby as you know).
By the time I finally went back about 4 months ago the physio said that my pelvis was the worst she'd seen, that it was twisted. She manipulated it back, which is evident from x-rays, but the pain is still there every minute of the day...
thats why I am going to see a rheumatologist in a couple of weeks to see if its something more severe.
I have no idea and my physio has exhausted all she knows to do. I followed the excerises until one of them pinched a nerve and I had to stop :/
I have a very high pain tolerance so I rarely complain, but I do take pain killers every day for it, like I said I cant function unless I do.
I carry my son around a lot which I know doesnt help, the same with your sling I guess, but what are we to do? We still have to keep living and being Mums! My son is 18 months old and only 10 kilos so I guess im lucky hes not too big!
Im not sure I helped, but I hope I shed some light on your condition.
I hope you find the right help for you