AirPods

I’ve had my AirPods for over a month and I’ve started to notice recently my left AirPod is muffled. I have to turn it all the way up to hear it but then my right AirPod is way to loud. What concerns me is when I take out the left AirPod it sounds like a speaker but when I put it in my ear I can barely hear it. What should I do to fix this?