Huge Rottweiler angry about his nail clip

My dog gets extremely nervous to the point of struggling and shaking every time I try to clip his nails or give him a tick treatment. It's getting so bad that my regular grooming spot won't cut his nails even if he's held back for the defeat, he could hurt himself.Is there anything (melatonin, Benadryl) that will safely "knock him out" so I can give him proper grooming once every couple of months.