Summeryet,
It might be the weather that's affecting your nails right now. Winter is particularly hard because of the cold, and dryness if your house is not adequately humidified.

I take vitamin E as well and had gorgeous nails over the summer. They have started to crack and split, and my cuticles get very dried out. A good hand lotion might do the trick. One thing I've noticed since taking the viatmin E is that my mails grow faster than weeds. So if they do break this time of year, they grow back in pretty fast.