What feels like my kidneys have been quite tender for a few weeks. at first i only felt it when lying down but now i can actually feel it all the time. it's not particularly painful though but is concerning.

Time to see doc: The way it sounds and providing you are right regarding your kidneys as the source of your symptoms and in the presence of side tenderness and urine changes you might have now an acute condition such as a kidney stone and/or infection in top of a chronic condition and that will have to be addressed promptly. Ideally you should start with your PCP or GP as having most medical information about you.