My skin has rashes and I don't know where they come from.

I have three problems. My first rash is near my lips and just started almost a week ago. It itches and now it is starting to spread. I do not know what it is or where it came from. My second rash started a couple of months ago. It is in the creases of my arms. Sometimes it flares up and itches and burns really really bad. It never really goes away I jus use cortizone to help stop the itch. The last one it started like three to four years ago. I just shaved  my legs and my aunt thought it would be a good idea to put bug spray on everyone. So after that my legs kept itching and now everytime I shave my legs or was it gets this big rash all over with a lot of red bumps every where. Can someone please help me?