Thanks for the info. I've checked with a couple of online pharmacies, one in particular - they show the product on their pages, but when I called they were all out. (And if one did happen to have some, they wouldn't be able to get more after they run out.) In the past I tried the quick release version. In my case, ER worked better. I guess I'll have to revisit the non-ER product.
According to the FDA there is a shortage (unavailability, really) of verapamil ER in the U.S. The manufacturer stopped making it recently, I think in February 2019. It looks like it is not available in any strength. This has been a miracle drug for me for cluster and I've run out and am now having a bad time. I'm going to have to try replacing it with regular verapamil. Does anyone know if there is a way to ask FDA to get verapamil ER made by another company, maybe as an orphan drug?