I am starting to feel an itch inside my vaginal lips, what can it be?

More info. More information is needed to help arrive to a diagnosis. Itching is suggestive of some sort of irritation, but the nature of it is unclear based on the amount of information provided. It could be some allergic irritation, friction irritation, reaction to a foreign body or infection but it depends on the history and other symptoms as well as physical findings on exam.