Yeah, if you just switched to the halides, it is probably a bit shocked by the increased light. You will want to move it down some and reduce the amount of time your light is on for now and then work your way back up. Think of it this way, it would be like someone who's been inside all winter goes to spring break in Florida and spends the whole day on the beach with no sunscreen.
It also very well could be splitting. I previously had one that looked just like yours, and it would look a bit rough every now and then. It did split a couple of times too. I also remember seeing the white stringy stuff, but I don't recall if it was during the split or not.
If your is like mine, it should be pretty hardy. Just give it a break from the lights, maybe do an extra water change just to be on the safe side, but I bet it will come out looking better than ever in a few days.