You might try to alert them of your presence, but that might not end up being the best idea. The girls that you were just hanging out with or happened to be around are now seemingly impossibly gigantic. Did someone do it? Did something cause it? Who, or what? Unfortunately for you, you won't get many chances to find out, as you have to try your best and survive as you're not alone.
One day, for reasons that escape your comprehension, you shrink really small (ranging from about 1/2 inch to 1/10 inch or 1cm to 1 millimeters approx.), and you don't really know why. (Formerly titled 'Giantess/shrinking & farts - Spending time with 'Auntie' Sheila')