The moral of this story is: Find something that works and stick with it. Do not be tempted to change anything without very good reason and unless what you have is not working.
But the biggest point once again is 'hooves don't lie', so listen to them before all others.
I have a rescue horse 'Grace'. It was a while before I could really address healing her feet, we had other stuff which was higher priority. Anyway, I was really chuffed this year when she became rock crunching in February. It all went horribly wrong in April when she was wormed with one of those long acting wormers, she promptly went footy and we have struggled ever since.
Her footiness was made worse when she was let out of her dirt paddock onto lush grazing by a well intentioned, but uninformed person.
Normally a bout of footiness if caught early can be quickly remedied with appropriate management. But unfortunately the long acting wormers sit in the liver and do their damage over weeks and months.
Equally unfortunately Grace also has EPSM. So resting her is not an attractive or sensible option and tweaking her diet is more than normally complicated.
We moved her onto a strict routine of exercise within comfort levels 3X a day. Turnout only in an arena. Hay soaked for 12 hours and then thoroughly hosed off to get rid of as much sugar as possible and any traces of chemical fertilizer.
Her feed was forage based, very low sugar, (but high in oil for the EPSM) and the minerals fed made allowances for the high iron levels we have locally. So we were doing the best we could with what we had, but were chasing the elusive rock crunching we had before spring. (I am going to have 'there is no magic bullet' tattooed on my forehead).
There is no published data that I can find which firmly pulls together the damage caused by long acting wormers and how to fix it with a horse that is both prone to laminitis and has EPSM. As you can imagine, it is a tough place to be.
Perhaps against my better judgement I tried a couple of new 'laminitic safe' products. One of which caused very unfortuate negative behaviour changes and the other which made her EPSM symptoms surface quite badly.
So we have reverted back to our normal feeding programme of:
Micronised linseed (from Charnwood Milling - less than £1kg)
Herbs according to need including lots of nettles and milk thistle
And from now on I will never use another long acting wormer, nor will I let anyone persuade me that they know better than my horse what she can or can not eat.
Touch wood, but slowly slowly her feet are improving and she is gradually returning to rock crunchiness :-)