Allergy or baby acne or something else...?

[Laurappo]

4 months old. Has these clusters of spots on face and neck. They look so sore. Baby seems to itch a bit but not massively. Is it too late for baby acne to appear...? Quite a lot of them. Will call GP in the morning but thought I would ask here.

For info he has been FF since birth, always on the same milk. No other symptoms but a bit grizzly now and then