Small bumps on my dogs right back leg?

my dog who is a male 7 year old dachshund/chihuahua mix and he just recently had fleas but we got rid of them from flea drops and flea baths. we gave him the recommended amount of flea drop and have only gave him two flea baths in the past week and a half. and so far it seem like the fleas are gone. but he still itches his back leg like crazy and he has been itching it so bad now there is a small bald spot (smaller then a size of a quarter) so i made my boyfriend check him out and near the bald spot where he is itching there is a small cluster of three small bumps they are about the size of this c < that c. maybe a little but smaller and if we touch them he crys like we ripped his leg off and a little farther down his leg is another small clusters of bumps the same size. does anyone know what they are? they are kind of dried out hard bumps i just got back from petco and bought him some oatmeal spray that is supposed to help with itching. i am wondering what do you think could be causing this could it be the heat change (it gets up to the mid-late 90's here) could it be something he is allergic to or something worse? im hoping this stuff works so far so good. dont worry if it stays longer then a week i am taking him to the vet i would just like to know if anyone knows what could be wrong with him and what could be causing this and what i might be able to do to help him not bite there or anything that can help :) thanks