Help and advice needed

Apologies in advance for the long post, I am looking for someone to give me any ideas on what could be the cause of my dogs illness as she has now been Ill for 22 months. My dog is a 4 an half year old Lhasa cross with shih tzu, she developed Myasthenia Gravis and mega-oesophagus at 11 months old after contracting Aspergillus Fumigatus, there have been no recurring signs of MG since stopping the Mestinon last year following AChR being back WNL, she has had the odd regurgitation and muscle weakness since but it’s not the same as when she had MG. My dog then started displaying true vomiting (sometimes without producing anything), lip smacking, malaise, something just not right following her season in Sep 2020. She was diagnosed with Hypoparathyroidism following ionised calcium levels being low and the PTH still WNL but very low. Started treatment with One-Alpha and calcium supplement, until developing PU/PD then ionised calcium levels went back to WNL. Even when my dogs ionised calcium levels were back WNL as the hypoparathyroidism seemed to be transient her nausea, emesis and malaise continued, having periods of being well then taking dips with really bad days, interestingly she also had the odd muscle twitching episode, she develops bad eyes every now and again, reverse sneezing, coughing at times, sitting down on walks, falling over, face planting the floor, random barking, staring into space, excessive borborygmi, being clingy, hiding when scared, being off her food and unable to settle at night. Her cholesterol levels have always been high (between 8.7 - 11.2) and ALT was always high until changing labs, now her GGT is now high and had an abnormal BAST, however, abnormal scan was clear. My dog was spayed in March 2021 and referred to internal medicine specialist June  2021 who indicated it could be CE however, she was given every possible gastrointestinal medication with no improvement. In Jan 2022 my dog started having focal seizures with saccadic oscillation (this occurred one week after stopping Omeprazol), muscle twitching of face and legs, she also started scratching at her left ear obsessively and my other dog licks the same ear obsessively too (had ears checked and swobbed no sign of anything) have said this could be OCD.  Started on Levetiracetam (3 months + now) muscle twitching still continuing but reduced and has had the odd focal seizure and one tonic-clonic, malaise, nausea and emesis has decreased too. She has had her thyroid tested, scanned twice, MRI (I have the images if you would like to look), CSF all unremarkable, full blood count (so many times), ACTH there’s probably more too, but nothing is indicating anything, she has been diagnosed with focal seizures and REM sleep behavior disorders due to most of the sickness and seizures occurring at night. While her symptoms have improved with 3 doses of Levetiracetam a day, something is still not right and I am worried we are just symptom treating and not finding the cause of the problem, her problems seem to be relentless and progressive. Thank you in advance for any advice or help you can offer, if you need any further information I can provide that too.