 [ Symptoms ] dark spots on inside of arm opposite the elbow what is it  the spots are wrinkly and originated after a trip to the beach i thought maybe a jellyfish stung me because there was mild irritation almost a year later the spots have multiplied and darkened what are the possible diagnoses [ Disease ] recurrent infection is strongly related to low water intake abd high urea so in my opinion you could be suffering some crystals or salts causing thus sensation so a urine sample and us is needed to confirm this while you need to boost up your water intake