Cut marks on tip of foreskin. Reference.

2-3 Cut marks on foreskin develops occasionally. Generally when I don't masturbate for long. I have a habit of washing my penis with water after urination. My blood test and sugar test also come normal. No previous problem of any kind and no medication. It appears when I masturbate after gaps or days. May be skin at top of penis is not stretched regularly when I don't masturbate regularly and when I masturbate after long the skin expands and gets cut...just an assumption. It is not a regular problem but occurs sometimes. What is the cause of problem and it's cure if circumcision is to be avoided. I take care of hygiene as well as I wash penis after urination. I don't understand why it happens. Please enlighten me with all possibilities. Attaching pics for reference.