My father woke up with the skin on his whole right arm dark red, looking as if his skin had been peeled off, looking raw-red. He has no pain and there is no swelling. His blood pressure is normal, his blood count is normal. His hemoglobin was a little low, but not serious. He also has broken blood vessels in the corner of his eyes. He takes blood thinners, so we were wondering if this could be an allergic reaction to a drug?