Aw, I totally get it, mosquito marks on kids are really annoying to look at! Honestly, a few of us use silicone gel patches (like Dermatix or similar) on the dark marks, tapos consistent sunscreen talaga, kasi ang sun exposure lang talaga ang nagpapaitim pa more. One of my mum friends swears by vitamin E oil din, ginagamit niya every night, and she says after a few weeks nakita namin na nag-fade na. The marks usually do lighten on their own in time, pero patience lang talaga, I know it's frustrating!