Did Prozac stop working for me or is this normal?

I am 17, and have struggled with anxiety and depression for the past couple of years. My doctor prescribed me prozac about 3 or 4 months ago. It’s been working really well, and I normally feel very much at ease and motivated, however the past couple of days have been hell. I am going to Africa in June and when I was at a meeting for it yesterday I had to excuse myself and I basically had a panic attack in the bathroom. It was horrible. That morning I woke up with anxiety as well, so this was all completely out of the blue. Today, I feel very anxious as well and I have no idea why.

Do some antidepressants stop working for people? Is this just a freak thing or do I need to talk to my doctor? Let me know your input.