Share 'Blisters... Bad Grip? Driving too much?'

So i've been working on my backhand, using the grip Feldberg shows in his clip on YouTube, and I'm getting blisters on the pad of my pointer finger... I have been throwing a lot of drives a day, so i didn't know if it was just that i was throwing too much, or if i'm missing something on my grip. Also i noticed that Nate Doss tapes that spot on his finger... So is this a common problem? Thanks fo…