Three times this week i've had a sudden onset of hot red patches (non itching) that felt like a bad sunburn over my hands, arms, knees and feet and middle back over the lower ribcage area. I had kidney pain for two days but no stones or burning in urine. Also the past week I have had temporary, but severe tremoring in both hands, throbbing chest pain on the left side of my sternum, My face gets pale, and mottling in legs after using the bathroom? The episodes last for about 10-20 minutes.. I am trying to figure out if this is a sign of a cardiac, kidney, or circulatory issue? Has anyone experianced this? If so what is it? please see photo.