<s>[INST] I have a blotchy, sunburn-like rash covering my arms. It stings vaguely. I haven t been out in the sun at all and it doesn t itch! Any idea what it may be? [/INST] Hi..dear user.., Thanks for choosing HCM., Blotchy sunburn like rash on arms.., could be Nutritional dermatitis...it is causedby., Deficiency of NIACIN..,(Pellagra)., So  follow., 1) Morning Calamine lotion ..on affected part.., it acts as soothing lotion gives cooling effect., 2) Night...Momentasome and gentamycin cream.., on affected part..ok., 3) Cap..Bcomplex and Zinc ., daily ., 4) Niacin tablets..ok thanQ </s>