After I Had Sexual Intercourse With My Only Sexual Partner

After i had sexual intercourse with my only sexual partner for more than a year, i experiemce pain in my vaginal area. I thought that the pain was only due to insufficient lubrication, because i had experience same pain before but only lasted a day. After 2 days, the pain still persists and there was already itching. I just kept on scrating my vagina to relieve the itch but it did not go away. So the next day, i decided to take a look in my vagina and found out that there were whitish accumulation in the opening of my vagina. I panicked and tried scraping them by fingers. The substance is whitish and cottage cheese-like, and smells like vagina. Then there was slight bleeding, i guess because i scraped them off. That night i checked again, the whitish substance werent visible at the mouth anymore, but i tried scraping my vagina again the white turned browish, but with the same texture. I had scraped more amount that night than in the morning and feeling the texture down there, there are still many left behind. I next morning, i had bleeding somewhat in the same amount of menstruation but i doubt it is period. But im not really sure. My last period was only three weeks before and it is irregular. What is happening to me? Is this an STD? Is it deadly? How can i treat this on my own?