As i'm going up in deadlifting weight, i find my grip gives way earlier than any other part of my body, making me lose reps because the bar feels like it's slipping off my fingers. I tried incorporating hook grip into the exercise, and while the bar felt a bit more secure, I felt my middle finger was rubbing against my thumb nail and making it feel like it was pulling it out, and causing a bunch of pain, and no matter what I tried it always came down to that when the bar left the ground.
Any advice?
Disagree with everyone advocating mixed grip here. That shit eventually gave me golfer's elbow and I have seen others get biceps tears from it. Stick with the hook- it is like having an infinite grip superpower once you acclimate to it. But it will take time.
Practice just doing it for your lighter warm up sets for a few weeks. Your thumbs will gradually adjust. What was once a sharp pain dulls into a comforting, if not outright pleasing, mild soreness (like a good DOMS on your traps after a heavy pull day). Taping the thumbs helps too. Get the self sticking, tearable medical tape. It's a lot cheaper than hook grip tape marketed to lifters.