Sad after mastrabating

I'm a teenager and have been mastrabating for a couple years but recently after I finish I feel this sad, ashamed, emptiness in me. The shame is not from society telling me it's wrong and blah blah blah, it's just after I'm done I'm just discussed at the stuff I was so into during the session (i.e. wired categories of porn I was watching that is just wired and kinda gross). But even when I don't feel ashamed, I still feel this sadness in me that last about 10 minutes. Please help me. Is there something wrong? How do I fix it? Thanks :)