Hopefully once she has passed this initial pain she'll be OK. She'll have to be aware of how she's doing things and lift correctly, etc. Easy for me to say, difficult for her with a toddler.
I found out about the joints in the pelvis by lifting incorrectly. I didn't even know the pelvis has joints. I was unloading supplies. I bent down, picked up, stood up & turned at the same time - repeatedly over & over. Twisting while lifting is a no-no. Now I pick things up correctly and then I turn my entire body with no twisting. No more pain.
I went to a chiropractic school for treatment - teaching schools have reasonable charges. After my back felt better they taught me the 'correct' way to do things. I also think I got better treatment because I had my own student and all his/her teachers - not just one individual in private practice..