Don't drink this stuff!
She may have kidded, and then got mastitis - is the udder soft and pliable, any redness, hard lumps etc?
She may also have developed an udder as a goatling - though usually a thin goatling will not have enough reserves to do that. Then if she has not been milked before (it is generally advised not to touch a goatling's udder other than to make sure she has not mastitis), this is the "milk" in the process of being re-absorbed by the body. You may have opened up her teats now, and now need to make sure she does not get an infection in her udder.
I would be very concerned about a very thin goatling - they should be plump and ready to be mated, without being fat. BUt if she did kid, she may be quite thin. I struggle not to get my goatlings fat, as do pedigree breeders in general. She may well be too thin to be mated this autumn....
Is this a registered goat and did you buy her un-seen? Does she have a CAE certificate and is the herd tested for Johne's?
Please get a vet to examine her.
If you want to reply by private message rather than on the open forum that is fine.