These purple spots are petechial spots and they are caused by leakages of small capillaries into the skin.This is because your skin has easy bruisability. Anemia and deficiency of vitamins C, K, B12, or folic acid are the common causes of easy bruisability.Try taking iron tablets and multivitamins for some days and see if the symptoms improve.
Other causes are alcohol consumption,liver disease,SLE,aplastic anemia and leukemia.
If your symptoms do not improve after taking iron and multivitamin supplements,then pls consult a physician and evaluate yourself for the above possibilities.
Hope it helps.Take care and pls do keep me posted on how you are doing.
Thank you for your response. I think you are right. This only happens when I scratch the part of the body that itches due to an allergic reaction. I have very sensitive skin that bruises very easily. I'll try to get more vitamin C, K, and B12.