Talk to Gastroenterologist on Possible Stomach Infection

Aoa, Last monday i may have eaten something wrong,i felt nausea and slight fever without vomitting with only one loose after that i started having slight discomfort at the left side of my abdomen just like something is inflamed..i felt nausea for three days but the inflammation like feeling is still present and worsens after bowel movement .i can still feel it if i take a long breath.I am an IBS-C patient also but i was managing well after this i am also having constipation with low stool outcome and tell me should i vist GP and ask for antibiotic or do something else?