Ball hitting ground off the tee

[shaymus]

This just started happening last week. I played four rounds and it happened about 4-5 times each round without any noticable change in my swing. I generally hit a high banana that goes about 240-260 on average. I use a 10.5 degree loft and this is the first time I've had this issue. The ball hits the ground after the tee and then travels about 75 yards. The ball mark is considerable as it seems to burrow or tunnel into the ground.
I'm new to the game this year and I recently took a lesson. The pro adjusted my grip. He told not to try and use the new grip while playing just yet, which is exactly what I started to do. Is it possible that this is the reason for my ground ball tee shots?