Hello April

If two different professionals have had a look then perhaps it is what has been diagnosed.
From the information given very little reasoning can be made and as you cannot be assessed it is even more difficult. Wikipedia reference-linkSIJ problems are very easy to diagnose so perhaps these professionals cannot have made a mistake with the diagnosis

Help us out with the following information to see what advice can be given

1) what happens when you stand on that leg?
2) bringing ur knee to your chest? what happens? what about bending foreward like you wanna touch your toes?
3)can you lie down on your left hip without pain?
4)is this pain constant or only there when you are walking?
5) does it disturb your sleep?
6) the SI pain and left tronchateric pain, do they occur at the same time?
7) any lowerlimb symptoms?
measure from ur belly button to the anterior superior iliac spine on both sides? anydifference in length?

The anatomy youv mapped out correlates also with the anatomy of the small rotators of the hip
7) what happens when u turn ur foot in and out against resistance in standing respectively (like against a wall)?

SI problems most often have a traumatic onset and there are different types (inflares, outflares, upslips and downslips), the often respond well to manipulation/mobilization to reset and specific exercises to reset and maintain.
some laxity may have been present in ur ligaments prior to ur D&E and the surgical procedure could have traumatized that...

hope to hear from you soon