I'm using vcool ice pack and the gel leaks. why does this happen ? I've only used it for a month. any solution or I have to get a new one ?

Honestly, I have never bought those gel ice packs before. I usually make my own -- I add ice cubes to one of those hot water bottle bags and use them as an ice pack of sorts. It's pretty effective.

Yes replace it immediately!! The substance used in ice packs are chemical and can cause harm.