TMI: this came out and I'm scared!!!

I've been sexually active for 4 weeks, and it's the first day of my period. This came out of the tampon I inserted 3 hours prior to taking it out. It looks like little bits of gut and when I wiped it with a cotton swab it was like a paste. I am totally freaked out.
My other symptoms are: itchy inside vagina, sore clitoris and sensitive labia majora 
My mother wants me to go to the emergency centre at the hospital because she thinks it may be more serious. Perhaps an STD or something worse...