Question about the pill? (Feanolla)

Hi, I know this sounds like a terrible maths exam question but I would like advice.
I had sex at 8 and 10am today. I took the pill like I always do at quarter past 1pm. I go to the toilet at 1:45 and realise I have diarrhoea. Am I protected? Should I get emergency contraception? take another pill? 
Please advise asap, thank you pals c;