Just keep on milking her. Congestion is nearly always nutritional most of ours went away when I stopped graining my does so much before kidding. Slowly starting them back on grain after drying up, just a handful really, and moving very slowly back to grain. I have no idea the mechanics of it but with less grain we simply have less congestion.
Now edema, where you put your finger onto the udder and your finger print stays on the very firm udder, or worse pitting edema where the udder looks like it has cellulite
that is sometimes CAE and my vet also thinks it's hormonal.
A friend gave me some salve in little tiny tubes one time that had dex in it, likely a DMSO base in petroleum. It was remarkable in getting inflammation out of an udder quickly, obviously wear gloves. Because I had no idea what the percentage of dexamethazone in the salve was compared to the mg/kg in my bottle of dex, I took the little tube to a compounding pharmasist and have a tube of it made for me.
Anything that you want to use topically that you are comfortable massaging into the skin, is fine, just know that without a solvent carrier it isn't penetrating into the udder and helping much. In severe cases or cases where a doe has a show to get to in a week, you can give anti-inflamatories via injection.
Don't start down the oxytocin road, that is about milk let down, and a doe with a congested udder has tissue that is inflammed it is not milk that needs to just be let down and everything will be fine.