Should my hand be hurting after I play the Nintendo DS?

I’ve been playing a lot of Nintendo DS. I am right handed, so I use the stylus with right hand and hold the DS with my left. My left hand it hurting in that spot between my pointer and my thumb. It aches only a little, until I have to use those muscles, Then it hurt significantly more.

Am I hold the DS wrong? Am I just playing it to much? or is not normal for it to be hurting from this little usage?