Squealing and "Flapping" noise

Hello! I was driving to work earlier this evening and my car made a new noise. There was a squealing coming from under the hood, which has been relatively normal when it is cold out. Today, however, I noticed it was worse than usual. I figured I had a belt that was going bad. However, when I was almost at work (I have a 30–40-minute commute) the squealing stopped and now it can be described as only a flapping noise. That is not the best description, but it is all I got because I have never heard this noise coming from my car. It almost sounds like a really old beater when it revs, but you would have to hear it to understand what I mean most likely. Anyways, I have another 40-minute commute home in the morning, and I am really concerned about how safe it is going to be to drive this car home. It isn't any of the belts that I could physically get to under the hood, and it should not be the timing belt because A) it still drove the last mile without an issue and B) I just had the timing belt replaced not even a year ago along with the entire water pump assembly. Any ideas? Thank you ahead of time.