On day 9 of first fast! Have some questions, looking for some answers!

Hi everyone! Let me first say that I love this cleanse! It's the first one I've ever done and it's the first one I'm doing. I even got other people into it and they love it too! That aside, I do have some questions.

Being that this is my first fast, is it ok to go longer than 10 days? Tomorrow is day 10 and I don't really want to stop just yet. I've lost a good amount of weight and I feel the best ever.

My friend that started is having some kidney/back pains. Normal? What's the cause? Any related stories?

Ok, so I didn't have that many questions. I was thinking of going for 15 days (then seeing what I felt like) and was wondering about it. Also, anywhere here NOT do the salt water flush? Man, that's a killer. What'd you do instead?