It is small and appears orangeish/yellow and has an M on 1 side and the number 751 on the other.

Where did you find it and why do you want to know what it is, please?

There are many pill identification sites online.
But if you know it's not yours, take it to a local pharmacy for identification and/or disposal
Better safe than sick and sorry

Does it look like this?

http://gsm.about.com/photos/photo_us_h/001/cycl002a.jpg