I used to get the same so now make sure my face cream routine in the evening extends to under my ear lobes, now they are fine.
I have a 4 year old and one year old and both get open sores where the lobe meets the face. I try and cream it but I don't always remember to do it everyday 🙄
I don't think taking the kids tops on and off helps as some of the neck openings are tight and yank the ears up. But I wondered if it might be a vitamin deficiency or something (although they both take vitamin supplements daily on top of their moderately healthy diet).