Lump inside vagina?

So yesterday while I was showering I felt a hard bit of tissue on the inside wall of my vagina facing the back, it was hard to the touch and kinda round? Like a lump I guess... Today morning I tried to feel it again but this time it was different, like it moved?? And I couldn't go around it like yesterday. Hard to explain... And I tried doing it again just to check and now I feel nothing! I don't know if it moved up or what...

Did this happen to anyone? Can anyone help?