buy gibson melody maker

Strings dont sound properly?
Hey ive bought some Ernie Ball strings and ive just put in the the bottom string in, none of the others are in and when i pluck the string it sounds very different due to it vibrating very much. I think it’s becuase the string is colliding with the fretboard. My guitar is a Gibson Melody Maker by the way.
It may have something to do with the pickup and humbucker as i took it out a few days ago and put it back in.
Please post your comments. Thank you.
1) You have re adjusted the bridge, the strings are set closer to the body.
2) You are in a lower tuning, and so the strings have less tension
3) something is wrong with the nut and needs replacing.
Gibson Melody Maker: Superstition