Sculpting creates "spikes"

Hi, Im new to blender, I have made a few models, but Im having issues with this one

Im sculpting the hair for a character, I started with a sphere, and Im using draw sharp to make the hair strands, but on some parts of the model, it just goes crazy and starts creating spikes and a lot of weird geometry… I have aplied the scale, I reset the brush, I dont know what can be causing this, any help?