Oh my gosh I know exactly how you feel! Except my gelding is 20 😂 I found the best thing for him was if he was being a dill and jumping around was to put him in to a deep low stretch in canter and it usually gets him breathing and relaxing again. While in the strecth I do some flexion work again. Then I slowly bring him up ahain and keep doing gentle flexion work, keeping the same rhythm and after doing a circle softly in a short frame I then take him large and do the same thing. Hope this helps, works for my old man!