swollen udder in dried off doe question

[Ellie Mae]

we got a call last night from an elderly friend to ask if we could show him how to give his NigerianX goat/doe an injection and to milk her udder as the vet told him she has mastitis.

She had a set of twins that were sold over a month ago and appeared to have dried up. Then two days ago one side of the udder swelled up, so he went to the vet for advice.

One side was completely dried up, and when I milked the swollen side, a good amount of "watery" liquid came out, and didn't have any milky look to it until at the end of emptying the udder.
I have never seen that before so am curious as to what that could mean?
I couldn't feel any lumps or bumps, the swollen side felt a bit warmer than the other, but barely.
We didn't take her temp, and she is eating & drinking well.

she is a tiny little doe (4yrs old) and running with 3 Nigie intact bucks that are huge in comparison.
So am wondering if it was more of an injury and the watery liquid was from swelling?
I observed the bucks being quite rough with each other and ganging up on her somewhat also.
we are heading over there later today to check on her and to help him separate the bucks into another pen and wanted to get some more info if possible.

thanks!