What Causes Pain During Periods?

I had a loop diathermy 3 weeks ago, and had discharge for about 7 days after due to the antibiotics! On the 10th day after my diathermy i started havin light bleeding and 7 days after that i was due to start my period, now ive had pains for the last week but nothing to say that i have started my period although i am still bleedin lightly! I went to the doctors yesterday for the pain and he had a feel of my tummy but it was painful like i was being stabbed is this normal what should i do as ibuprfen n parcetamol are not relievein the pain