Quick update: About a month after the clipping, her nursing had gone from extremely painful to slightly less painful back to extremely painful. She was very tense all the time while nursing, and her jaw was like a vice. I tried to find someone else locally to look at her tongue, without luck. At the same time, I called my m/w for her recommendation on a CST. The woman that she suggested I see is also a chiropractor (as a pp suggested).
We saw her for the first time on Monday and she was wonderful!

: I still don't fully understand what the CST is doing, but I know that the change in DD's nursing has been dramatic. She even stuck out her tongue, ever so slightly, but passed her lips! We went again today and the therapist worked on a couple other issues. DD had definite tightness in her TMJ and palate issues as well, which have both been helped by the CST. I can feel such a big difference in how she holds her mouth now.
We'll follow up again next week, but I am very optimistic. I really want to thank everyone for the recommendation to see a CST. Her little tongue is still very "short" and I can see that the tie is very broad-based, but I'm hopeful that CST will help us overcome these issues -- from a different angle.
