Converting a X/Y Axis Rotation to a Pitch

I am trying determine the pitch of rotation. I can grab the Euler angles of the rotation, but while the z axis of the Euler angle is the correct Yaw, the Pitch is expressed in the X and Y together in a way I can't quite make sense of.

My current findings show that when :
YAW = 0 THEN
EULER = <PITCH, 0, YAW>

YAW = 90 THEN
EULER = <0, PITCH, YAW>

YAW = 180 THEN
EULER = <PITCH, 0, YAW>

YAW = 270 THEN
EULER = <0, PITCH, YAW>

I've thought about using the deadly quaternions but I really can't get into deep study of them at the moment.

What I am trying to accomplish is essentially moving an object in the rotation angle of the avatar by a certain amount (although a unit vector could easily be multiplied for longer lengths).

Does anyone have a clue as to how I might go about solving this rotational dilemma?

*Problem Solved*

After some experimenting I determined that multiplying a vector by the rotation(quat) was the best solution.