red itchy bumpy rash

ok so i never get any type of rash then 2 days ago i noticed a few little pimple like red bumps on my arm then about 4 hours later it was all over both arms so its now been 3 days and its very itchy and red but the bumps are so close to eachother that they look like clutters of red itchy bumps all over both arms and the top of both feet...it looks like heat rash but isnt ... dont kno if its an allergic reaction tto something because theres nothing i used or ate that was different please let me know what this could be

[AngelNikole]

Soo recently like about telwo weeks ago on friday I notice a bump on my tummy, it itch like crazy and then the next day I notice more coming  then on my back came more then my chest, even my boobs, on my neck and some around my thighs, they seem pretty similar to what yuh guys say, they itch like crazy and when I look in the mirrior after I take a shower it scares me I hate having these all over my body, its not right they itch very bad, but when im at school they dont, like during the day they dont but at night they start to itch like crazy its like when I itch them more and more come, there not bloodu or pus or anything, there just little bumps all over and red. Please if anyone could help please.