Kim,
I may not be of much help because I've never heard of Chanca Piedra, but it seems like you have very little to loose trying it because if you don't it sounds like you'll have to have surgery anyway. I'm assuming that's why you went to the doctor and got the ultrasound.
since you have a doctor, you should keep in contact with him/them while doing a flush though. Also I'd suggest the Olive oil with grapefruit juice and a straw, it sure goes down better.
...OldPilot