Impossible to tell anything without seeing the swing and I agree that a pro would get you back on track a lot better and quicker than even the best on here.
Same swing does both, it just depends if you get your hands to square the club at impact.
Could be many things, so lessons are a good advise.
It comes from an over the top swing, leaving the club on an out to in path. This could be caused by casting, or it could be caused by not starting your swing by clearing your hips. It could also be a swing plane that is too upright.