Problem with opacity being linked to pressure sensitivity in Photoshop cc

Recently, whenever I apply less pressure to the brush tool it gets a much lower opacity. To achieve an opaque line I have to press down much harder than is good for my nib. I've tried every possible opacity and pressure sensitivity slider, but nothing seems to change. The problem was also affecting the fill tool, as it comes out at around 20% opacity, even though the interface shows opacity to be 100%. This problem is making coloring exceedingly difficult, so any advice would be greatly appreciated.