USB Drive not recognized by Mac OS X Yosemite

I have a USB drive I setup as bootable with a few different Linux distros using Multiboot in Windows.

This afternoon I plugged it into my Mac to look at the list of ISOs on it. I then ejected it from the Mac.

I plugged it into a Windows PC and booted off of it and booted Linux, did a few things and then rebooted the PC into Windows with the USB drive still in. Shortly after I booted Windows I unplugged the USB drive (without doing Safely Remove in Windows)

I plugged it back into my Mac and I get the error: The disk you inserted was not readable by this computer. With the options to Initialize, Ignore or Eject. If I ignore I can see it as /dev/disk2 in terminal.

diskutil repairDisk /dev/disk2 gives the error:

Unable to repair this whole disk: A GUID Partition Table (GPT) partitioning scheme is required (-69773)

I have a Windows 8.1 VM on my Mac with VMware Fusion, if I load the USB drive in Windows in VMware it shows up just fine.

Any idea what could have happened or how to fix?