Stretch marks are getting deeper but no weight gain

Lianna

Soo ive had stretch marks on my stomach for years because im on the bigger side. But they were almost impossible to see unless you were looking for them. Now they are getting deeper and they are noticeable but i havent gained any weight. I weigh the same that ive weighed for years. I havent had kids and i had my period so i cant be pregnant. Its just weird to me that they are gradually getting more noticeable and deeper without any weight gain or anything. What can cause that? Has anyone else had this happen? Im just confused why theyre getting worse lol