My Left Big Toenail On The Left Side Is Slightly

My left big toenail on the left side is slightly raised, and splits when it reaches past the toe. In the past when I trimmed the nail, some times the nail would come away for the skip of the toe while cutting with nail scissors. Why is it happening, and what can I do to prevent further problems down the road? The is no other color but white so could I have been trimming wrong?