Blender Sculpt brushes don't function properly I have a really hard time explaining this, but I'll try.
My Brushes don't work flowy and soft like they did before, they just make really weird strokes. like multiple sharp edges or bumps instead of one single smooth line, and i really can't do anything like that. Every brush has the problem of not working precisely and just make the weird sharp stuff all over the place. The only thing still working is smooth. I already tried a lot with resolution, Dyntopo and stroke adjustments, but nothing helps. 
The problem started pretty sudden, I noticed immediately when i started sculpting. I updated my blender version, but that doesn't help either. 

I added a picture, where i tried to draw a single line with SculptDraw in the mouth area.

I'll hope someone can help or explain.
I was having this issue too. I don't know why this is occurring but I can confirm that Mr Zak's solution worked for me.  

To clarify on his instruction:


Create a backup of your work
Switch to object mode
Select only the model you want to sculpt (you can only choose one at
a time)
Press Ctrl + A
Select Scale from the pop-up menu


The fix is complete and you may now switch back to sculpting if you wish.