Red Spots

I (62F) have been getting red spots randomly on my arms. Someone told me that it's common when you get older. Mine are a little strange looking sometimes, like two stripes once-in a pattern. I don't know why I get them so often or how. One minute they're not there, the next minute they are. This picture is from today. I went to an exercise class (for seniors, so nothing too strenuous). When I got out of class, these were there (they weren't there when I went in). I don't know if you can see it but they are raised. I've never had them raised this much! I've barely ever even had them raised. What is happening?

https://preview.redd.it/i7its4ndc7jh1.jpg?width=3024&format=pjpg&auto=webp&s=0dce8bd73e8756552455fe56ff7a2be6fb9843d7