swollen labia with a hard lump?

I noticed I had what looked like a pimple on my labia towards the top. for about 24hrs the one side was swollen 3x its normal size. its finally shrunk back down and the hard lump is gone but its a bit itchy. unsure if the itch is from the Epson salt bath I took since I'm sensetive to baths and tend to get yeast/bacterial infections easily. I have not recently been sexually active and I'm in a committed relationship so don't suspect STD's. I've had a cyst before but that was more towards the entrance not up top. anyone experience this?