I think the best thing to do is keep an eye on it. Don't freak out but just notice if any of them change in size or formation. There are other spots that develop on skin as we get older, and most of them are not a health concern. The top of the head is tender from being covered with hair for years, and if you have fair skin this may be greater for you. I have gotten a lot of spots on my head since shaving and have noticed they fade quite a bit in winter, so the Doctor is probably right with what he said about the sun. Use sunscreen to minimize this effect.