Smooth brush is not working correcly I'm currently learning to use blender, this is my second project its a character, now my problem is that i have used the smooth brush before and already know how its supposed to work (at least without changing anything).

Now I haven't changed anything in the settings of the brushes (or at least not on purpose) here is my problem: 

I'm currently sculpting some details on my character but when i try to smooth this:



It ends up like this:



Now the problem is that the smooth brush smooths some parts and others are left with little spikes that wont get smoothed out no matter what I try, I have dyntopo turned on and I already applied all modifiers to the mesh so there are no modifiers activated. 

Like I said before I'm a beginner and I'm currently learning, I have tried to look online for answers but I could not find any, thanks ahead!
try this:

enable dyntopo, then in the options bar above smooth shading, enable relative detail, what relative detail does is that no matter how much zoomed in or out you are, the size of your strokes will be relative only to what you set in the size options of your brush.

next zoom very close to the part of the abdomen that you want to smooth, and smooth it with the correct sized brush, in theory, that should work.

it should also be noted that the more polygons you have in there, the more gentle the smoothing will be, you can read more here:

smooth brush is destroying my model,what is happening?[SOLVED]

sources for my claim:https://www.youtube.com/watch?v=tZnUgt659oI   [at the 14:15 minute mark]

hope it works.