We all slump from time to time. Some of us more than others and some of us much worse than others. A slump can be like quicksand. The more you fight and adjust, the deeper into the slump you go. Before you know it, you have tried everything under the sun, changed everything under the sun and have lost what you did have to begin with. It's like walking through a maze in the dark.
Here are some things to keep in mind that might help you get out of the quicksand sooner and snap you right out of the slump.
90% of a slump is in our heads. The other 10% is mental.
If you are thinking miss, you are gonna. Just have the confidence that you are going to make the shot. if you don't you don't. But you absolutely cannot be thinking about missing.
If you are shooting tentative, you are guaranteed that you are not accellerating through the cue ball. This restricts not only our ability to make balls, but we lose position too.
I am willing to bet there is a good possibility that you are doing some guiding as well. Concentrate on keeping that stroke smooth and straight and try not to cast the cue during the stroke. Lack of confidence causes this effect.
Relax and shoot like it means nothing, but also like it means everything.
Another common issue I see when a player is slumping is they tend to raise their heads off the stroke too soon to see how badly they missed.

Love to gamble with these guys! LOL
Of all of these, ralaxing and accepting what is about to happen works the quickest for me. I find when I do this, I start dropping balls and getting position again. Then comes the confidence and you are back on fire again.
Last but not least, if all else fails...Put on some knee and elbow pads, then wrap a rubber band around your prized pair. Hurts like hell, but you can bet your A$$ you aint gonna be thinking about missing!!! Oh, the knee and elbow pads are for every time you hit the floor (Which will happen after each and every stroke) If you aren't hitting the floor, you don't have the rubber band tight enough. Works for me every time!!!
Good luck man. The shanks suck for sure!
Kevin