I looked up calcium channel blockers and found:
•Diltiazem (Cardizem LA, Tiazac), thus I conclude we are taking basically the same thing. I went to Diltiazem to get the lower cost, and also lost the slow acting, thus I have to take my mediation twice a day. I can't remember if the change also relates to the loss of swelling in my ankle, but as said I no longer have that side effect and I continue to take Diltiazem twice a day. I think the "LS" in the Cardizem stands for Long Acting, as in Slow Release...an nice convenience, but I didn't think it was worth the extra cost.
I am on another brand/generic calcium channel blocker - Diz..don't recall, but I can check. I take what I think is the maximum does and had some of the symptoms you mention, but none real bad and my body has adjusted.
Swelling of ankles was the the side-effect I most noticed, as did my wife. But it was not noticeable when dressed (a man) and I didn't have trouble putting on my shoes. I discussed with my cardiologist and he recommended I give it more time. I no longer have swelling of the ankles, or I have gotten used to it (ha !!).
I'll check back and try to look to see if you got any suggestions, I can even look up the one I take but I don't see anything in your brief post that would make me think you'd have a different initial side effect problem I take. One advantage of the one I take, in regular release and twice a day, is low cost.