It does sound like it could be Sandifer’s. The problem is that it’s hard to tell sometimes. I have heard of doctor’s thinking that kids were having seizures when they were really having Sandifer’s symptoms, but I’ve also heard the reverse. I would try to videotape the episodes and then show it to your doc. If it persists on a good dose of meds, and if you’re still concerned, then you can ask your doc for an EEG. If it remains normal, then maybe that would offer you some peace of mind.
My dd had very severe Sandifer’s. Our doc worried about myoclonic jerks, and I was pretty sure it was Sandifer’s, but went for the EEG anyhow. When it came back normal, they were more comfortable assuming that it was actually Sandifer’s. The behaviour did stop as her reflux pain reduced.