What Causes Scant Pink Menstrual Bleeding With Vaginal Itching?

hi, i am due on my period and have all of the usual symptoms, back ache, cramps etc... i started bleeding today but it was just a spot of pink and then no more. later when i went to the toilet, i wiped and there was more blood, but not as it usually is.... it was lighter and a pinkier red.... also, there was a pink cottage cheese like substance when i wiped.....my vaginal opening has also been very itchy, i know this may be a sign of a yeast infection but im a bit worried as i have never had a yeast infection in my 23 years of life.
i had unprotected sex about 2 weeks ago....and now my period doesnt seem normal and i have this weird discharge with light bleeding, which ive never had before.....my mind is working overtime due to the worry. id really like your thoughts as to what this could be.
thank you so much