Lump on Inside Wall of Vagina

I have never had sex or participated in anything close to it, and am just a teenager. I do masturbate on occasion. I have never had any serious or notable medical problems in the past. I recently noticed a lump on the wall of my vagina around the size of a golf ball or a large cherry that is in no way noticeable from the outside. I can push it back against the wall of my vagina a little ways, and this doesn't cause me any pain or soreness, just a bit of slight discomfort, like I'm pushing on something that doesn't want to be pushed. The only kind of consequence you could say that I've "suffered" from because of it is that I get a little sick to my stomach after touching it, but this could very easily just be because of the confusion I feel or just the strangeness of the whole thing. I could swear that it's moved; the first time I discovered it I felt it closer to the opening of my vagina, and the next couple of times I've gone to check it, it has been farther back and may or may not be smaller. The end of it either touches the other wall of my vagina or at least comes close to it, and the end is slightly rough but only vaguely. If anyone has an explanation of what it is, why it is there, if it is serious, and what is needed to get rid of it. If there is a way to treat it without telling my parents and going to the doctor, I would love to hear it, just to save the embarrassment and awkwardness. However, I do understand that I will most likely need to do both. Any contributions to helping me with my concerns are GREATLY appreciated.