problems with yeast and discharge

I've been having some problems with yeast and discharge lately, it started as basic discharge - clear to lightly yellow colored, and lots of the nasty cottage cheese-like substance. I've had yeast infections before so I didn't worry much. But mid last week, I started to notice small flesh or white colored bumps (only one or two at a time, and so small that the only reason I noticed was due to me washing myself and feeling the small rise). And then, this morning I noticed a huge (well, not huge to normal people I'm sure - about 1/4 the size of a  pea) and very, very painful blister-like bump on my vaginal lip. There is only one.

I just, I don't know what it could be. I fear it's something like herpes, or worse; I hope it's just an ingrown hair or a treatable (temporary) condition like a cyst. I can't imagine myself having an STD and to be honest I think it is completely unlikely. I would literally have to be the unluckiest woman on the planet. I have only had sex once, nearly a year ago, and while it was unprotected I really don't even like calling it sex. Neither of us "came" and the entire ordeal was insanely short lived (five, maybe ten minutes). I do masturbate, but I don't think that could be a factor since I am (as stated) a bit of a hypochondriac and thusly anal retentive when it comes to washing my hands/self/etc. 

But and STD is still possible, we were unprotected after all, and that worries me! So I'm just not sure what to think; I have every intention of going to the doctor - but appointments tend to take forever for me to get so I have all of this paranoia ready to build up... So I decided to ask for opinions? Help?