3D Camera math is off

Game Mechanics
#1

I’ve been trying to get back into 3D for a few days now, and I decided to make the camera. The problem is that when I rotate around the z axis, the rotation is actually applied to my movement in such a way that the y position of the camera rises a little if the z rotation is not 0. I’ll show you my code:

if (Keyboard.isKeyDown(Keyboard.KEY_A)) {
			float yrotrad;
			yrotrad = (yrot / 180 * 3.141592654f);
			xpos -= (float) (Math.cos(yrotrad)) * strafeSpeed;
			zpos -= (float) (Math.sin(yrotrad)) * strafeSpeed;
		}

		if (Keyboard.isKeyDown(Keyboard.KEY_D)) {
			float yrotrad;
			yrotrad = (yrot / 180 * 3.141592654f);
			xpos += (float) (Math.cos(yrotrad)) * strafeSpeed;
			zpos += (float) (Math.sin(yrotrad)) * strafeSpeed;
		}

		if (Keyboard.isKeyDown(Keyboard.KEY_W)) {
			float xrotrad, yrotrad;
			yrotrad = (yrot / 180 * 3.141592654f);
			xrotrad = (xrot / 180 * 3.141592654f);
			xpos += (float) (Math.sin(yrotrad) / walkSpeed);
			zpos -= ((float) (Math.cos(yrotrad)) / walkSpeed);
			ypos -= ((float) (Math.sin(xrotrad)) / walkSpeed);
		}

		if (Keyboard.isKeyDown(Keyboard.KEY_S)) {
			float xrotrad, yrotrad;
			yrotrad = (yrot / 180 * 3.141592654f);
			xrotrad = (xrot / 180 * 3.141592654f);
			xpos -= (float) (Math.sin(yrotrad) / walkSpeed);
			zpos += ((float) (Math.cos(yrotrad)) / walkSpeed);
			ypos += ((float) (Math.sin(xrotrad)) / walkSpeed);
		}

And my mouse code:

public void updateMouse() {
		mouseX = Mouse.getX();
		mouseY = 720 - Mouse.getY();

		mouseDX = Mouse.getDX();
		mouseDY = -Mouse.getDY();
		
		Mouse.setGrabbed(true);
		
		xrot += (((float) mouseDY) * .090);
		yrot += (((float) mouseDX) * .090);
		
		if(xrot > 90){
			xrot = 90;
		}
		
		if(xrot < -90){
			xrot = -90;
		}
	}

Obviously this is a trig question, but I’m not the best at trig (taking it next semester), so I don’t know how to fix it!