Hi Elise,
While I can't comment on the CBD oil, I wanted to mention that Ban Xia Bai Zhu Tian Ma Tang is a consideration in the dogs with nausea and mucousy emesis and stools. It has Tian Ma as well, just like the TMGTY, so may have the same anticonvulsant benefits as what you're seeing. Just a thought in case these signs persist
If it did help, then it would suggest food allergy, especially to grains, as a potential cause of the seizures
As to CBD, I don't see any reason not to try it while you're exploring these other options. Meanwhile, continued good luck
Steve