It's definitely quite bizarre that there are now at least 3 reports of it happening in the DC area. In one case, someone's dog was also reported as simultaneously being affected. There were also unrelated reports of another dog being affected (vomiting blood, among other things) in a hotel overseas. In both cases, humans and adults were simultaneously affected, and the symptoms both were experiencing wouldn't make sense if it were just a dog reacting to their owner's anxiety.
I have no idea if it's microwaves, and I'm not quite sure if the DC attacks are real, but I think there likely are some sort of deliberate attacks occurring against US diplomats and spies. Maybe a collection method that's inadvertently causing harm, at least.
Here's an interesting article on it: https://www.gq.com/story/cia-investigation-and-russian-micro.... I wouldn't be surprised if some of the cases are psychogenic (someone hears about it and then thinks they have it, etc.), but I suspect the majority are real.