Horrible cramping

Last night I was woken up with awful awful cramping in my upper abdomen. I have been having Braxton hicks but this was not those. This morning after I've been up for a bit I went to the toilet and there was a bit of pink blood when I wiped. I haven't had sex in 3 days. I'm 32 weeks tomorrow. Baby is moving fine but I just don't know if it's something to be worried about.