I was bitten by sandflys two nights ago, but it seems there are more than yesterday, even though i've left the area. why is that?

It could be anything: either you were bitten in more than one place, but you did not get a reaction until later. or by scratching the old bite, you were able to spread it around. either way avoid scratching, because it could get infected, use hydrocortison and alternate with topical antibiotic on the bite site. take benadryl (diphenhydramine) at night to avoid scratching while you are asleep. good luck. i hope that answer your question.