Suggest Treatment For Swelling And Itching On Labia Majora

randomly today one side of my labia majora started itching, so i went into the bathroom and scratched. nothing new. about an hour later i noticed the same area was throbbing, so i went back into the bathroom to check it out. it was swollen and a little bit red, and just got worse as the day progressed. i went home and took a hot bath and it helped during... but when i got out the pain was even worse. it stops hurting when i lay down but when i get up the pain comes back again, worse than before... and it seems like it just keeps swelling. what's going on? i'm incredibly uncomfortable and worries. thanks.