What should I do? He has no other symptoms. He's 9.5 months old. He has been a little clingier than usual ... but that's it.
Rashes are tricky. That looks like it could be from heat, or if could be from a virus. My kids get a similar rash on their bellies and back when they get sick. Even regular colds can cause a viral rash. If it's not bothering him and he seems healthy, there's not much to do but keep an eye on it.