Period or not?

Basically I've been a week late on my period this month, me and my partner have had unprotected sex about 4 times, where he has finished inside me. I've had slight cramping and
​This morning I woke up to find a pinkish/red colour fluid in my underwear and when I wiped. I'm unsure whether this is my period starting or whatever... Shall I still take a pregnancy test
​Help would be appreciated?