I'm dealing with premature ejaculation and nightfall, finishing within about 10 seconds during intercourse can this Diltiazem 30mg Tablet help with that?

I want to be upfront with you here diltiazem is a medicine for blood pressure and chest pain, and it isn't something used to treat premature ejaculation or nightfall, so I wouldn't expect it to help with what you're describing. What you're going through is common and very treatable, but it needs a doctor who can look at the whole picture stress, hormones, and sometimes specific medications made for this purpose. Please bring it up with a physician or a urologist rather than trying to manage it with a medicine meant for something else entirely.