Hi Lida,
I have no advice, just a word of welcome. Your story resonates with mine, and I am only a few weeks further into this journey than you are with my 15YO OTTB.
We had no clues except for horrible abscesses in each front, which have dragged on and I may have contributed to that and the subesquent laminitis and rotation by giving him antibiotics and bute- which I did not know (at the time) could lengthen the process of an abscess from start to finish.
Babe is sleek and shiny and has heaves, as well. I thought heaves was enough and had struggled to come to grips with the idea that there was more going on with his health at this point than just a couple of bad abscesses. Two months in, he's still recovering from them.
I also worried about the side effects of pergolide (Prascend). Vet said start him on a half dose and within a handful of days, he looked like a zombie.
I stopped the meds and turned here. Learned about APF and titrating (building up) the dosage. Ordered the product and restarted the procedure of starting the pergolide. 
I don't see a zombie now. Hang in there and read as much as you can and ask questions as you go, folks here are terrific about offering their experience and expertise about this path we're on.
Anna

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Anna Dolly
Keyser, WV
Sept. 2020
Babe's Case History
Babe's Photo Album