chin & neck area rash >?<

About a month ago I had an itch on my chin; scratched it & then a huge welt appeared.  It resembled a welt like a mosquito bite.  Another welt appeared as well.  These "welts" erupted on their own with just clear liquid but then I awoke & felt like tiny bugs were crawling under my skin.  I have no insurance but I went to my family doctor & he said it looked just like a rash, gave me some hydrocortison cream & sent me home.  The only relief I can get from the itching is using benadryl pills but they keep me feeling too sleepy.  I have searched the web all I can & don't have the $ to go to a dermatologist....does anyone know what might be going on under my skin?  This is driving me crazyyyyy!  I have not changed anything; no medications, no detergents, no makeup....nothing.  That's why I can't figure out what is making my neck area feel like this...it itches, feels like bugs crawling under my skin, then makes welts appear & the erupt on their own...someone pleaseeeeee help me!!!!   ANY suggestions are greatly appreciated!