Iphone 4, caller cant hear me? Please help

Okay my phone was working fine but all of a sudden I am having some issues. I can hear the caller clearly and loud. However they cant seem to hear me, they can hear me to a certain extent but its very low. Even when I put it on loud speaker it does the same thing. This would only happen sometimes but once I would turn on and off it would work for a bit.However that doesnt even work anymore. When I was having these problems at first it didnt effect facetime, but now its affecting that as well. I recorded some sound and played it, that seemed to work fine. I really dont know whats going on so please help me.Thank you