my iphone got bad stereo speakers after a while

I've been a happy iphone user for a month or so now but a week ago my speaker suddenly became crap. It's are very low. Talking is fine. Also using the earplugs is fine.
On my friends phone, when you hold your thumb over the left speaker while playing music the sound goes low, naturally. But on mine it wont. Left or right speaker, it doesnt matter. Audio is still low. Tried restoring twice now. Also tried the unplug earplug trick and iVolume. Nothing works. Is it just vibrate for me from now on or can anyone help me with this.
When ringing, if I hold my ear onto the right speaker i can hear the audio just as fine as if i'm holding it onto the left speaker. I thought the right one was mic.

Thanks

iPhone got no right speaker, it's a mic.
However, after a while mine also sounds crappy.
Probably played music too loud and blew the speaker.

hmm, think i read somewhere on the forum that the speaker could not be "blow". Just tested something. Could be a coincidence though. Did a test, set my friends phone to the lowest volume and my phone to my highest and they sounded the exact same.