What Leads To Tiny Bumps On Face,neck And Stomach Area?

i have little bumps on my face, neck and stomach area.. but it looks like allergies and i went to the clinic and he told me it could be because of the cold weather, i got an allergy test not to long and it said i wasn't allergic to anything but i don't understand why this is happening to me, i took reactine and it didn't help, what can i do?