Hymen Myth

I m a 21 year old girl,i am in a rellationship from past 2 years.we
indulge in sexual activities like oral sex.we enjoy quite a healthy sexual
relationship however we have never had intercourse.
Last night my bf licked my vagina
for a long time and even fingered a bit but only on my clitorus.Later
on i saw some blood coming out of my vagina.I am not sure whether it was
due to licking or  was it becasue it was my fifth day of menses.
This blood was red blood in color and dint smell like normal menses
blood.This bleeding stopped later on.
I think since i am not able to see my hole it means the hymen is still
covering it and my hymen is intact..
I dont think my bf went too deep while licking, but still i am really
worried that is my hymen torned?can u please tell me how does one come
to know whether their hymen is intact?Does it pains when Hymen breaks?
I have examined my vagina there's no difference,I still cant figure
what's hymen?and how does it look like?