How can I stop hurting myself while masturbating?

I am 15 and have been masturbating for about a year now. When I first started it was usually just once per day and I was fine. Now I have moved on to 3-5 times per day. The only problem is that whenever I masturbating I seem to feel burning or tear my skin. I usually don't even notice it during. It hurts a lot now though. I feel like I can't stop. I was thinking about using lubricant, but I really don't want my mom to find something like that in my room. How can I still masturbate a lot, but reduce the pain of constant rubbing? Thanks.