How To Treat Bumps On Legs And Arms?

i have bumps that look like mosquito bites showing up all over, i have on my leg and many on my arms about one on my finger, and like a few on my back and hip. i wash my sheets and i looked for bed bugs, i though it would be mosquitos but its fall and where i am living its getting pretty cold so mostly they are all dying out. they will apear in random places so its not a rash type.