Bloody! I think you have my horse... bay standy(?) mare... & you can keep her! I've had horses for... many decades now & while I've had the odd vet bill over that time, I've always actually been a bit perplexed at people saying 'horses are accident prone'. Until we got Whinny. I'll tell you about her so you don't feel so alone
She somehow scratched her face not long after we got her, bad enough that she has permanent white scars... & there have been a few more white scars since, from... who knows. Then she got her hind foot in... something and I discovered she had a 'cankle' from a 'rope burn' minor looking injury to the fetlock, no blood even. Got the vet who proscribed keeping it wrapped a few days & giving her bute initially. But it didn't go away, got worse, despite me having vets out to see her 3 more times. She's remained fat up to the hock ever since.
Then a few months after that, she was tied, short & high, but somehow managed to get her hind foot(yes the same one) over the rope - spose scratching her head - & got stuck, fought it... by the time I cut her loose(thank goodness I was close, it was less than a minute), she had a bloody 'rope burn' around that ankle, and when I got the chiro, he found(surprise!) she was all kinds of 'out' from that trick. She has run into fences, fallen over playing at... not much in the paddock, then a few months ago I noticed a hard swelling on the side of her hock(same leg), which vets xrayed & told me it's a 'spavin'(osteo arthritis tho she is only 6yo), but in the last couple of months, it has grown(how did it come up so quickly, get so big so quick??). I sus she was probably kicked while playing, or she fell & bashed it or some such... She is not lame & it's not the least sensitive, just a big, hard lump off the side of her hock. Then, as she likes to JUMP in & out of my stock crate, she jumped out, slipped & skunnied her legs. Then yesterday I discover she's got a bunch of minor cuts around 3/4 fetlocks(amazingly not THE hind foot...).
So... after hearing about yours too, I don't think I'll have another bay mare. They're accident prone. Just like yellow ones are Houdinis - well at least my old Pally & my current buckskin are, so they must all be. So's my yellow dog too BTW, so that PROVES it!