Google aroma therapy for horses. Its natrual herbs that helps with all different things. There are herbs that can help with calming your horse.
Hope this helps💜
hmm I know your struggle - I have an ex stud who goes absolute bronco on spring grass,so with him I try put him in the paddocks that other horses have been on first (so he gets their stubby leftovers) but this obviously might not suit you if your horse is harder to keep weight on also put out hay piles as hay is a filler and if he fills up on hay he will have less room for sugary grass, also yarding him for small sections of time in the day will minimize his grass intake. But perhaps the best of all these is toxinbinder I hear it works wonders on many of my friend's horses,however it doesn't work on my boy but hey hope this helps :)