IPhone 4s Mic Isn't Working

my iPhone 4s is about a year and a half old, working mostly great until last week. I may have accidentally dropped it, and now the mic doesn't work. Whenever I call someone, I can hear them but they cannot hear me UNLESS I put them on speaker phone. Once I do that, they can hear me perfectly. Siri also cannot hear me; when I hold the home button to talk to her and that white line appears at the bottom, I'll talk but it doesn't wiggle to show that she's hearing me. The keyboard microphone is the same way, and when I try to record a voice memo it doesn't 'hear' me either. So, as far as I can tell the only way I can be heard is via speaker phone, and Siri is useless now :/ I've tried cleaning the mics on the bottom with a can of pressurized air, to no avail, and I've looked up similar problems on these threads but I've never found one with all of these issues at once, it's either the phone calls don't work but siri and the voice memos are fine, or else siri won't work but everything else is fine.

Info:
iPhone 4S, iOS 7.1.2