Re: help pls!

Are you using any skin products?

Your skin is constantly chnaging and growing, to me it seems you lack collagen and elastin in your skin layers that normally prevent stretch marks. That could be the reason you're getting them although you're not losing or gaining weight.
You should try to apply some stretch mark prevention cream first, or some home remedies like aloe vera and olive oil etc..
You can find more info here: http://howtogetridofstretchmarkseasy.com