Ultrasound detected something on Lower Left Kidney... Help?

I have been having two separate pains, one has been for years. The one for years turns out is my gallbladder, I was morbidly obese before and they couldn't detect the stones. I have lost over 100 lbs and had an ultrasound a week ago. The results showed something with my gallbladder (no surprise) and lower left kidney, which is where I have been experiencing pain for a few months. I only know the results because the receptionist told me, but I don't get in to see the doctor until monday to find out more details. She just said something came up with gallbladder and "there is something with the lower left kidney". She did say hesitantly that it is nothing dire. Does anyone know what it might be with the lower left kidney? I know nobody would know without seeing the ultrasound, but trying to figure out the possibilities.
The pain when I get it is a throbbing ache that really hurts, when they did the ultrasound on that area it hurt like a mother.

[Paderla Anitha, DNB]

Hello and hope you are doing well.

The most probable guess would be a kidney stone or a complex cyst or a tumor. It could even be a hemangioma, a collection of blood vessels. But difficult to tell.

Hope this helped and do keep us posted.