MSK is basically a birth defect in your collecting ducts.
This is a good newbie article on MSK, so it won't delete it I will have to put a space in there, remove the space to use the link:
Hope this helps answer you questions,
WELCOME to our community. I am so so sorry you have having so many problems but you are in the right place. Lots of veteran members here and newbies who are here to help you!
Not sure on the potassium, but Urocit K many of us take who make calcium oxalate stones. have they sent your stones out to see what kind they are?
A good Uro or a Nephro is the way to go and sometimes it takes a few to find the "right one".
Welcome and sorry to hear about your diagnosis. Definitely try to get in with a neprologist if you can. They are more interested in preventing more stones and the overall health of your kidneys, where a uro is more able to deal witht structural problems and obstructions.