Is it normal that sometimes get a cyst on my vagina before having my period?

Okay well for awhile my period has been coming late like it'll skip like a month. I always used to start at the end of each month. Now it starts like in the middle of every other month or something? I don't really know cause I'm not the type of girl to keep track and stuff on things like this but I know it's been coming a little late these past few months almost a year.

Maybe it's cause I've gained weight in a short amount of time. Maybe it's because of stress. I have no clue. But the question is, is it normal to get cyst before starting your period? This happened to me a few times in my life. It's happened a couple times recently like I started my period like 2 days ago and I had a cyst on my vagina a week before I started.

It's still going away but it's big and when I squeeze them pus comes out then blood, I'll keep squeezing until everything is out. Should I leave it alone? Does this happen to anyone else? I don't shave. I shave at rare times the last time I shaved was probably in November. But like I said this happens before my period sometimes. What does this mean? I asked my sister if this happens to her she said no.