What Causes A Bulge In The Back Of The Vagina?

With a vaginal prolapse does the bulge sticking out reduce in size sometimes? I have a duck egg size bulge at the back of my vagina about the size of an egg. Im having a lot of lower abdominal & lower back pain, can t hold much in my bladder and feel like I want to have a bowel motion all the time. I don t strain to go, I keep going to loo and if it doesn t come out I return repeatedly until it does. I m not constipated, its just having trouble coming out. My Vagina has been quite sore and I am aware of this bulge thing all the time. My GP couldn t examine me yesterday when I went for the first time, as his nurse has left for the day so. He gave me a form to have a scan and also vag cream to use for 5 days. The scan cannot be done until next week and GP will see me after he gets the results with view to reefer me to a gynaecologist. I used the cream last night, it is only a 5ml dose but have been discharging as in damp but not saturated, all day which seems a lot more than the 5ml that went in. I had quite intense lower abdominal pain last night which felt like period pain & was in my lower back also. This afternoon I checked and I can t see the bulge. I still have the same sore feeling and have to empty my bladder frequently today. I have had a bowel motion today and it was a lot more than I have been able to pass lately. I m just curious as at this stage don t know what the protrusion is that I have and have to wait until next week to know more. I ve had all the above symptoms for several weeks or longer but hadn t had a look there until 2 days ago so that is the first time I saw the bulge even though I have felt it for a long time. Sorry my Q is so long!