Could Blood In Stool Be Related To Phenoxymethylpenicillin?

Been prescribed Phenoxymethylpenicillin for a throat infection. But I ve noticed that yesterday and today I ve passed bright red blood in my stools. The first happened yesterday and it was not heavy but enough to see from far back on the tissue. Same today. No bleeding until I went to the toilet. I do suffer constipation as I take sertraline and zapain 30/500mg. Could it be related to the penicillin medicine? I m scared. I m only 21.