Three things about that yogurt, 1. Milk can be "insulinogenic", a high insulin response even though little impact on BG 2. Gluten and casein share a similar amino acid sequence and 3. If you are talking about something highly processed like Carbmaster yogurt, it could be loaded with stabilizers and additives made with wheat.
Here is a long thread on dairy, but has many good links and discussions in it
http://forum.lowcarber.org/showthread.php?t=450127
Why am I going on about this beside your BG? Wheat and Dairy can be inflammatory, and many people, including me, see resolution of joint pain with a wheat and dairy free diet.
http://www.wheatbellyblog.com/category/joint-pain/
I had arthritis in the knees which went away in about a month, and bursitis in one hip that took much longer, but now haven't had any pain in almost three years. If you haven't read Wheat Belly, highly recommend it, also it has a list of the many names wheat hides under in processed foods.
Full disclosure..I also stopped doing yoga. Have a hip joint that genetically is more limited in range of motion than others, and opening the hip movement was more aggravating than helping.
Trader Joe's carries a liquid extract stevia, just a few drops, one drop can make the difference between sweet and yucky.
You should at least give the RD a piece of your mind. Have you heard about Diabetes-Warrior.net? Check out the diabetes forum too.