... wireless Shure in-ear monitors and the feedback went straight in to my ears, OUCH!
If your in ear monitors were loud enough to cause feedback to your microphone, then they were probably loud enough to damage your hearing many times over without causing any feedback.
I'm not really sure how you managed to build a signal chain where your in-ears were able to produce feed back, but it must have been so extreme in some other part of the signal chain that it probably damaged some other pieces of gear along the way.
Feedback is controlled through gain, and equalization. Dynamics processing isn't really part of that equation and just using a compressor isn't going to help you reduce feed back. If anything, it will cause more feed back as the purpose and usage of a compressor is to keep the levels below a certain point. If you compress the signal, and then boost it up after compressing it, that's only going to cause more feed back since the
entire signal (not just the transients which the compressor is working on) will now be louder.
If you want to reduce feedback, do it with a better microphone (super or hyper cardioid pick up pattern), a tighter monitor wedge, less gain, better EQ, or lower the ambient stage volume. Compression isn't the tool to accomplish what you are trying to do.