Can rough pressure on the clitoris cause pain in the moment? and very light spotting after? what is the cause of spotting?

Of course, any rough pressure can cause pain, and if the person causing it won't stop when you ask, that's battery. The cause of spotting, in this case, would be from trauma, either to the vaginal walls if penetrated or somewhere on the external genitalia. Your partner needs to be sensitive to the fact that they are harming you even if it is just minor injury. If they don't care then lose them.