If you got what might be mistaken for a mosquito bite, but if the effect and itch hangs on a lot longer, and it’s in a well covered (and usually tight) spot, say, under a belt or under heavy socks — it might well be that a chigger has drilled you. They don’t actually burrow into and stay under the skin, but, they will stay “on” a “bite” until dislodged* - usually by scratching caused by the itching. They may be rubbed to a new, nearby location by clothing movement across your skin, resulting in clusters of “bites”.
What I do if I think I may have been exposed is rub a little isopropyl alcohol onto my feet / ankles, waistline, and, yes, crotch, scrotum, etc. (Sorry to be graphic, but, chiggers drilling into a private part “ain’t no fun at all”.) Alcohol based hand sanitizer works too.
(This also seems to prevent, for me, if applied right after exposure, poison ivy rashes. I suspect it breaks down the urushiol. Most any solvent or potent soap will do, but a small bottle of sanitizer is convenient to have on hand. Urushiol is really nasty stuff - it can hang around and stay active on surfaces for years.)
(No, for any wise-*** reading, I don’t need to do this for poison ivy exposure to private parts — ever!!)
If I have an itch or any redness started from any of these causes, I upgrade to acetone based nail polish remover, or even just acetone on occasion. (Acetone will flash off much faster, which may or may not be considered a positive.) Acetone definitely seems to diminish the itching, and it most definitely will immediately kill a chigger. I suspect it penetrates the skin somewhat, and disrupts some of the chigger’s enzymes it was using to dissolve a little bit of YOU. SFAIK, light exposure to acetone on skin is not terribly harmful. I sure would not soak in it, however!
Thanks for the advice. Thankfully I have never been bitten even though I have lived in the woods for over 30 years. So I thought we must not have them. At least I’ll know what to do.