Thank you everyone, sorry I had to post and run! You're analysis was really helpful, it's always more difficult to see these things yourself. I didn't feel bad in this outfit, but now I know why I didn't feel as fab in it as in some other stuff lately.
Also thanks for the sympathy. I do hope we're going to find him a nice companion! The vet gave my mum the number of a guinea pig breeder in a nearby town who's also taking old guinea pigs when they're left alone and/or the owners can't care for them anymore. We'll see if there is an older female there whom Oskar gets along with and then we'll take that one in foster care. Whether we keep it or give it back when it lives longer is up to us I think.
Pil, my sister wished for them when she was small and they were a present for her, but they've fast become family pets. I agree that they have a good life with us, I was always sad when I saw one alone in a tiny cage in a flat somewhere. They're normally outside the whole year, in a big movable cage my father build (they're like lawn mowers) in summer and in a hothouse in winter. We only take them inside when it gets very cold. And they have free run of the whole garden when there's someone to look after them, the pics were taken on one of these occasions.