So I picked up a cheap mic because recording on the cell phone, uploading the recording and downloading it again is kind of a pain in the butt. Anyway, I'm placing the mic in front of my amp and recording it into the computer via Audacity. I'm getting this weird oscillating effect from somewhere and I'm not sure what is causing it. It's a weird fading in and out effect.

Oscilationeffect - Instaudio

Is it because of the cheapy mic? Or do I have some settings I need to adjust somewhere? I don't have a sound card so the recording is being processed on the motherboard of my computer; maybe it's that? Anyone have any ideas?