Injury Rash or cut?

So my Abyssinian girly has two hairless patches right behind both ears that she's always had, and she likes it when I rub them while I hold her. So last night I was doing that and noticed on the right side she had a little red irritation, either a rash or scrape of some sort. I know it's not ringworm, and highly doubt it's mites as she has no other symptoms, no hair loss, no scratching, no mites symptoms, ears look great, her health seems fine and her behavior is normal. I checked the rest of her body and everything else is perfectly fine (I also checked my other piggie as well of course.) Now my husband claims it's eczema, which I don't think at all. It also seems to have gotten a little better since last night, and when I touch it she doesn't seem bothered at all. Could it be a cut maybe? I'm thinking maybe Luna was barbering her and bit her...I noticed she had done some barbering to her a few months ago but it never happened again so I didn't think anything of it. Or she's constantly kicking her igloo up and dropping it on herself (clumsy like me lol) so maybe she hurt herself? Any ideas or advice would be helpful.