Diarrhea after conception

So I ovulated on the 26th of January. And me and my boyfriend have been having unprotected sex in hopes to have another child ( had a miscarriage in August ).. But Ive been told before that you have diarrhea the day you conceive and some days after. Is this true? If so when should I take a pregnancy test?...my period came on on the 12th & last for five days ( 28 day cycle ) ..... Or am I just overly excited & the diarrhea isnt a symptom and I just need to hold out for a while until I miss my period .