strange lump

I have an unusual lump on the outer lips of my vagina at first I thought it was a spot as it had a white head and I did pop it, however it's quite hard and red now(days later), i have no idea what is it ? It is not any sort of sti or std as I have only had sex with one person who has only ever had sex with me too, he has nothing wrong with him either and we had been having sex for a long time so I do not think its that! Is this normal in women ? This is the first time I have ever had a lump like this... Please help