Suggest Treatment For Pain In Waist

hELLO.....For 2 or 3 weeks I have been experiencing pain at my waist, left side, upon standing after I have been sitting.Rate it a six. Seems to have gone up over the last 2 weeks from a four. It only hurts upon standing after sitting. It goes away in a couple minutes as I go about my activivty. I thought I may have strained that area, but this is a pain that I have never had before ( I am a 65 year old relatively active female). I don t seem to have other symptons. Thought it might be kidney stones, but I see no discoloration in my urine, neither do have any pain upon urinating. I do have to push out the last small amount of urine when I urinate. Been like that for a few years. No fever. No vomiting. Mmmmm? Charlotte