Severe lameness in IR horse under vet/trimmer care


I am the caregiver the past approximately 4 years (not owner) of this horse:
19 year old draft dam, Friesian sire mare
Approximately 15.2 hands.
Overweight since I've known her, more so after her dam, who she's always been pastured with, died about 3 years ago. Living solo since but has 50+ cows in next pasture.
Cresty neck developed gradually,  approx 18 mo ago. Annual vet check and vet didn't bring concern to owner.
Intermittent lameness, became more problematic, vet put on bute. On bute for probably a year before I got owner onboard with a new vet. Changed to Previcoxx this spring.
Diet: on about an ¾ to 1 acre of weedy pasture. About ¼ to ⅓ if it is limestone rock outbreaks.
Free choice first cutting hay in a slow feed hay net - mixed grass with a little bit of alfalfa. I've had it tested at Equi-Analytics.

June 27, 2022
Finally got new vet in to look at her.
Insulin resistant 
X-rays show 10.8 degrees rotation front left and 14.6 degrees front right.
Possible abscess in right front observed on x-ray. Poultices with Epsom salt goop.
Vet started on Platinum Performance hoof supplement, Thyrol supplement on a 6 week step down schedule and switch from previcoxx to bute 2 grams twice a day
Begin feeding soaked hay.
Start 30 day stall rest 

Trimmer came and trimmed 4 days after vet visit, which was her scheduled 6 week trim. Vet emailed x-rays to him to go off of.

Continue supplements, meds, retrim in 2 weeks. Trimmer said she'd have good days and bad days and lameness remained fairly consistent. Retrim at 2 weeks and he took off heel mostly. No signs of abscess.  Things going along fairly the same until last Monday, June 27, when she was not wanting to weight bear on right front. Absolutely hoping lame.
Had vet out same day. Difficult to get her to stand square, wanted to park out but got xrays. Rotation on left 4.6, right 11.5. unsure if the right has additional rotation. No gas pockets noted on x-ray and positive for hoof tester all around hoof. She is standing with the hoof tipped, resting on the toe. She doesn't want to walk on the sole. She'll drag it back to back up and tip toe hop on a forward step. 

My question, how long can an abscess brew? How do you know it's something else? 

When I figure out how to attach the x-rays, I will.

Thank you,
Novice horse owner of my own little cob.

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