Vaginal Itch , Soreness dryness on Depo Provera

Hello. I am a 19 year old, sexually active female with some disturbing issues. A little background: I have been on the Depo Provera shot for 10 months, I have had brown spotting for most of those 10. I was diagnosed with Chlamydia, but after taking antibiotics and being retested, I was cleared.

The recent problem: I have been experiencing extreme itchyness constantly. My first thought is/was that since I'm wearing a pantiliner for the spotting (which I change regularly) that the moisture could be causing a bacterial infection. This itch is located on the outer labia of the vagina, nothing inside. Also, recently, intercourse has been extremely painful due to lack of lubrication, leading to light pink spotting afterwards. The soreness is most likely due to all the scratching. There is a light odor, but nothing to cause alarm; it just smells like period. There are no bumps, cuts, lesions, etc., and I do not shave. I have been with the same sexual partner for two years, so there's no viable risk of STD's. Could this be a yeast infection, or is the acid content of my constant bleeding causing this uncomfortable situation?

Thanks ahead of time,

Confused!