I've never tried to put a USB PIC to sleep.
But the datasheet has some warnings about putting the USB module in "Suspend" mode before going to sleep, and using the Resume bit to "wake-up" on USB activity.
See section 17.2

Could be tricky.

120ma sounds pretty high.
Try disabling the USB module and VUSB regulator and see if that's where it's comming from. The datasheet doesn't seem to list the current for the USB module.
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