I get bumps on the outside of my vagina. This has been happening for several months now. What could be the cause?

I get bumps on the outside of my vagina. This has been happening for several months now. What could be the cause?
Need more info? Painful, raised? Length of stay?

Not painful but they are raised

How long do they last? Any material inside of them? Age of subject?

I'm 28. I can't tell how long they last because its almost continues. I get them pick them they bleed then they go away and then I get another in another spot