They can evaluate your kidneys with a urine and blood test. X-ray would be 2nd step and probably more expensive? Maybe go to an ER where they take indigent patients? This way, if you can’t pay out of pocket, and since you are not working, maybe they can take the hit? Regardless, they are required to treat you by law and cannot turn you away. Also, ERs have more capabilities than urgent care. A lot of urgent cares will send you to LabCorb or something like that to outsource your labs. Best of luck to you but get it checked out as it seems debilitating and you deserve solid quality of life, especially after surgery and weight loss.