I think the dentist filled a cavity of mine without drilling first.

So I went in today to get a deep hole/groove checked out, since it was aching when I chewed on it and especially sugary foods. The doctor told me it wasn't a cavity, but that a filling I got as a child must've fallen out. She then proceeded to clean it out and fill it, even though I told her I was pretty sure that wasn't the case and I was 99% sure it was a cavity. Now it still aches, and I don't trust that she made the right decision. Bear in mind I could be completely wrong. Thoughts? Should I be worried? I can update this in a while to let you all know if it still aches if that'll help the diagnosis! Thanks.