Microphone Issue : your thoughts appreciated

[FitChicago]

Good morning folks:

Somehow this weekend I began having an issue with the Optimus' built-in microphone, essentially no one can hear me/can barely hear me during phone calls. My guess is that the mic is obstructed but I am not sure how to clear the mic hole. Can someone please help? (also what are the other possibilities if it is not an obstructed mic?).

Thanks, in advance, for your thoughtful feedback.