Thanks for your query.
I will try my best to provide you with best possible professional recommendations to your questions.
If it is due to insect bite and there is only redness
and pain at the site of the bite, application of ice is adequate treatment. Clean the area with soap and water to remove contaminated particles left behind by some insects.
Refrain from scratching because this may cause the skin to break down and an infection to form. You may treat itching at the site of the bite with an over-the-counter antihistamine. Calamine
lotion also helps relieve the itching. Minimize your exposure to insect bites
In my opinion if you are not sure whether it is insect bite, then he should be evaluated to rule out worm infestation. like thread worm. In case of worm infestation, de worming should be done.
So i advice you, firstly prevent exposure to insect even after that if rashes appear go for stool examination of your child.
Yet again, I do hope that you have found something helpful and I will be glad to answer any further query.