If your nut was missing the jack probably twisted/turned while you were plugged in. This would result in the internal wires twisting - causing tension on the wire resulting in the wire pulling loose from the solder point - resulting in the grounding problem.
Take off the back plate to the control cavity - look at the wires leading from the input jack - there should be 2. Are they solidly attached? If not you need to resolder them - very easy to do and saves you cash and time from going to a repair guy. Seymour Duncan's site has a ton of wiring diagrams - here's
link to them.
Your Caddy probably has 2 humbuckers, 2 volume controls, 2 tone controls and a 3 way - so here's the
link to that wiring schematic. On the schematic you'll see 2 wires from the jack - a hot and a ground. Check the ground wire and also check the wire that goes to the bridge to ground the guitar.