I just came from the Doc with the exact same symptoms. She doesn't know what it is either. I'm having a ultrasound of my kidneys on Friday as I also have a stone in the left kidney,so I'm going to ask the technican to scan there plus around the front of my pelvic area to see if anything shows up. Hopefully this will tell me something. I also have to visit physio as the Doc feels that it could be just a big knot in a muscle.Noticed you wrote this in Apr? Did you find out what yours was?

A week ago, May 29,'09, a couple of hours after weightlifting, a large knot (approx. 3-4" across)came up on my lower back just below my waist. There was no pain. The next morning, there was a bruise. The knot is smaller and flatter now and the original bruise is fading but there is also an old-looking bruise that appeared this morning that looks like a band going across my back to the right just below my waist. I'm still not having back pain but the bruised area is a little bit sensitive to the touch like any bruise would be. By the way, I'm a 56-year-old woman who's just trying to build some muscle mass, NOT a body-builder!

hey am 18 years old i am 18 weeks prego and i have kidney stones one stuck in my tube and more in my kidney but that on the right side now i have lower left sharp pains and i was having the pain shoot back to my back and when i was showing my boyfriends my we notice there is a knot there does anyone know what this could be

Mine went away in about a month. Still no clue as to what it was or what caused it. Put a bag of frozen peas on it for a few days. I'm still working out the same but no recurrence.