I cannot confirm anything without examination but it can be due to hives. Hives (medically known as urticaria) are red, itchy, raised areas of skin that appear in varying shapes and sizes.Many cases of hives are "idiopathic," meaning no cause is known. Others may be triggered by viral infections or medications.
Pls take some antihistaminics like Benadryl or Claritin.Apply some calamine lotion when the rash appears or some mild steroid cream.If the symptoms persist then pls consult an allergist.
Hope it helps.Take care and pls do keep me posted on how you are doing or if you have any additional doubts.kind regards.