She looks a lot like my daughter's mare (skinny wise) when she first got her. Even though we fed and wormed that mare like crazy, she didn't gain an ounce - until we finally convinced my son-in-law that the mare would not voluntarily wean the colt she was nursing (colt was 14 months old!!!).
The mare is still too thin, but she's gaining weight relatively rapidly - if 75 pounds in a month is fairly rapidly...
My mare had bailing wire braided into her tail. Literally braided. I think the previous owner's young daughter was trying to make Dancer "look pretty" and forgot to take the wire out. It was an unholy, solid matted mess - and full of garbage. It looked like it had been there for years. I spent hours
trying to brush it out. One day she got it hung up on a tree branch and we had to resort to cutting the mat off just to get her free. Poor girl. I bet both Dancer and your Clare are glad to be able to swing their tails again!