Doe with slimy milk

My friend called me yesterday with a question about her Saanen doe. She said that while milking yesterday morning she noticed that the milk seemed thick and difficult to squeeze out, and when she strained it through a washcloth, it made it really slimy. I told her to do the dish detergent test, and she said the milk turned really slimy and disgusting, so I'm assuming she has mastitis. The only thing is, she isn't showing any signs of discomfort during milking, and isn't swollen at all. I told her to put hot compresses on the udder, massage it with peppermint oil, and gave her some dried sage to feed her. Is there anything else she should be doing, and why wouldn't the doe be showing any of the other usual signs of mastitis? She is coming to the end of her lactation and is currently only being milked once a day. She's not producing very much as it is, and this morning had even less than usual.

Thanks!