Thanks for asking the question. It can be an allergic reaction to the medicine, can be a viral rash also. If your child had taken Crocin before also it is unlikely an allergic reaction to that medicine. Some things I want to know, when you started the medicines? Whether your child is having vomiting or wheezing. If it is a viral rash we don't have to worry usually but will have to rule out the allergic reaction. So a close examination by a pediatrician is necessary. Another thing is that maxtra medicine is better to avoid at this age. Another possibility is insect bite, most commonly mosquito bite or allergic reaction to any other allergens.