Are There Any Side Effects Of Taking Levonelle?

Hi, I took levonelle on the 6th of August and within 12 hours of having sex on the 5th of August being on the last day of my period, I was fine for a week but on the 14th of August I started to feel sick and get stomach cramps and then after going to the toilet to do a wee I noticed a very small trace of blood, then on the 15th August I was still suffering with feeling sick and cramping like you get on a period, then on the 16th of August till today the 18th I have diarrhea i woke up this morning with stomach cramps and now its as though i am on the last couple of days of my period where you get blood mixed with like a dark brown bloody discharge, considering i only finished my period on the 5th August my next shouldn't be due till the 30th September as I am as regular as clockwork, i take it these are all side effects of taking levonelle if so how long will the bleeding last? and the stomach pain etc... thanks I am 44 years old 5ft 9 tall and 14stone, not on any meds or haven't got any other health issues.