This is not something that I can find much about on the internet. I was hoping that someone would have heard of this before or could provide information about what this could be.

There is some kind of hard mass inside my vagina. It can be felt if I push on the left side of the front wall. It could usually be felt about in inch away from my cervix, although I can't always feel it as easily. Sometimes it feels as though it extends all the way to the left side of my vaginal opening. 

I get frequent back pain, especially on my left side, and I quite often have a feeling of pressure in my pelvis. I have also noticed that I have a very strong pulse on the left side of my abdomen that never used to be there.

I originally thought this was uterine prolapse, but I can feel still feel the lump when my cervix is high. Unless my uterus has literally fallen upside down and is resting on my vaginal wall, then I can't see it being prolapse. Although that's exactly what I'd describe the mass as feeling like.

If I look at medical diagrams, the lump is kind of where my bladder should be behind the wall. It's too hard to be my bladder, so could it possibly be a tumor, either in my bladder or between it and my wall? 

Before my period, I'll often get what feels like a very hard vein (feels like a wire/ ligament) that pushes into my wall from the left side of my opening to the right side of the back of my vagina/ cervix. 

Could this be a tumor of some kind? I've been having problems with this for about 2 years and haven't really had any new or worsening symptoms. If anyone could provide thoughts or insight into this, then I would be grateful.