Brief Answer:
Most likely, of allergic origin

Detailed Answer:
Hello

Thanks for asking on this platform

I have seen the image.The redenned lesions which are four in number and not very well circumscribed on neck and upper chest appear to be due to some allergy.
It may be due to insect bite or allergy to cloths,pollen,dust or any food item.
I would like to know
1) if you have noticed allergy to any substance,
2)whether there is associated itching,swelling or any breathing problem.
3)any similar history in past
4)whether it is progressing rapidly

The associated itching and elevated lesions suggest these to be of allergic origin.
Here anti allergic medication like cetrizine,benadryl and Steroid ointment helps.
If you have noticed allergy to anything,try to avoid those to prevent recurrence.

I hope this helps.
Please get back to me if you need any clarification.
Wishing for your child's good health.
Regards

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