You’ve exceeded the posting limits. Please try again in a few minutes.

I'm trying to answer a person who is trying to help me, and I get this message: "You’ve exceeded the posting limits. Please try again in a few minutes."

I read elsewhere that it happens if you post repeatedly in less than 30 seconds--like a spammer--but I didn't do that.

Also, if you know, how long is "a few minutes." It's been 10 minutes and it still won't go.