The pill is a yellow and oval on one side it has 650 on the other side it is either O M or W O, What is this pill used for.

Best bet, don't use or take pills that are not yours,

If you find medication throw it away.

If you have unused medication that you do not know what it is, take it to your drugest, he can look at and know amost all drugs.

I think this link will answer your question
Pill Identification Wizard - Drugs.com (http://search2.drugs.com/imprints.php)