What Causes Pain In Back And Thigh?

hi, i'm a 67 year old female with arthristis in my back and knees, have high blood pressure, 2 ulcers, acid refluex desease have had a heart attack 25 years ago, and now have kidney problems and i'm wandering why my back and thighs hurt so bad yesterday when i went to get another blood test on my kidneys that they used a wheel chair to get me to my car. could you tell me what you think may have been the cause and by the way still feel the same today.