What Causes Vaginal Itching?

Ok let s start with this I have sensitive skin and soaps and pads can irritate me and it can get itchy on the inner part of my vaginal lips. It s not an excessive itch I usually don t notice unless I accidentally scratch it in my sleep and rub it until it s raw and then it s really itchy. The past week had been like that but I wasn t worried because it s happened before and as soon as I switch soaps it resolves itself pretty quick. The moment I became worried was when I noticed a lump about the size of a marble (maybe a little smaller) on the left side right at the opening of my vagina. I had not noticed it before and now I am worried because I do not know what it is and the fact that it happened as the itching was present scared me even more. My last std testing was in February and I do not believe I have contracted any stds since then. I thought I might be getting a yeast infection since the itching hadn t gone away but I have not noticed any discharge other than thicker whiter fluids during intercourse. Should I be worried? What could this be?