Lumps on face and neck

[EventingMad]

My 5 yr old has these lumps on his neck and sometimes face he has had them for a few days now on and off! They look like bites but they don't seem to be bothering him at all! Does anybody have any idea as what they could be?
Thanks

 

[Llwyncwn]

Could it be a protein rash? Have you changed anything in his diet?