Bummer about your recording.
It definitely doesn't sound like any cellular RF interference I've ever heard. It does seem to happen when the sound levels are highest. I'm on the wife's computer, so I can't see the waveform. Have you inspected it for clipping?
Barring that, it could be a physical defect. That's what it sounds like to me. A loose solder joint (or loose connection of any kind) could be the problem. Perhaps the high SPL of the show the night before vibrated the connection loose. Or, if the SPL was high enough, it could have physically dislodged the microphone. But it does sound more like a loose connection to me.
Forget about trying to fix it the recording. There's no "plugin" that I'm aware of that would do it. Working with a "pencil tool" would be time-consuming at best and would likely sound "wrong" when you were done with it. Good luck!