Any help appreciated

Before anyone says to go to gp iv already been twice.

My son came out in a rash about 4 weeks ago i was 1st dr told me it was chicken pox but then after the 2nd week it was still spreading all over again so gp said it wasnt that and gave me piriton and hydrocortisone cream and said to come back after 7 days.

Back again after 7 days and had started to clear, now it has come back again waiting for another gp app but iv mentioned different things to them and they seem to think it nt any of it.

They said its nt hives, chicken pox, hand foot and mouth. We dont have any animals. It appears like this then he scratches and it starts to get a top and bleed. At my wits end now has anyone seen this and know what it cud be. He also has no fever or anything with it

Update he does have a cows milk allergy but he has never been affected this way from it. No animals but there are alot of cats that would pass our garden, could this do it?