‘I’m stumped’: I put $3,000 on my credit card during a vacation and my credit score plunged. Why is it so volatile?

“I pay for almost everything with credit cards.” (Photo subject is a model.) - Getty Images Dear Quentin, I pay for almost everything with credit cards, which I pay in full every month to avoid interest. I have done that for as long as I remember. I use them for convenience and reward points. A couple months ago I ran up maybe $3,000 more than normal because we were on vacation. My credit score went down immediately. It went right back up after I paid that card off. I understand that credit score is base ...