When you say greens, do you mean spring greens? I thought you'd decided not to chance these with him?
If you're going to try cutting things out, I would just cut out the "greens", whatever they are. My reasoning would be that if you cut out greens, herbs and dried forage and just give him hay, you won't know what, if anything, has been a problem for him.
I know it's difficult for you to source them, but I would really recommend that you try to find some Brambles and feed those as often as you can.
As far as the three products that you've mentioned go, I've not used any of them so can't really comment on whether they would be helpful to Sy. I can't see that any of them are going to hurt though and who knows they might be beneficial. However, as with cutting out items of food, I would try him on each one individually for a while, so that if he does improve you will know what has helped.
I'm sorry, you must feel quite upset by his recent episodes. Look on the positive side though, you have managed to help him each time
I hope that you find something that helps.