I broke two strings in exactly a week. Both were my top string (I tune to CGCF). So when I broke the low C the first time, it was a GHS .115 and it broke less than 1/8 of an inch from the nut. Then tonight at practice I broke the low C again and it was a .125 Rotosound. It broke again right below the nut yet again. Why? The first time I did a bass slide lead in into a song and it broke. The second time I was was playing staccato notes on the first fret and I broke the string. Is there a possible reason for this? Or did I just run into an inferior string? The first one I had had on my bass since July so it was well used, the second time I had the string for one week, and it was on it's 3rd practice. Any advice or experience is appreciated.