We typically play on small stages and my vocal mic is set up within 5-10 feet of the amp. I sing background vocals. Feedback is so bad that sometimes I turn the mic off for most of the night and only sing when absolutley needed (rare ). It's a low-mid kind of muddiness that kills our sound. It's definitely coming from my amp and mic. Is it my amp? Should I get a gramma pad? Is it my mic (SM58) or cable (with on/off switch)? Is it my cheap mic stand? Pointing the amp and/or mic away from each other doesn't seem to matter. Some rooms are much worse than others. Anyone else have this problem? What works?