Does Ovulation Stop Immediately After Conception?

Hi there. I usualy ovulate for 2 days. Me and my husband are trying to get pregnant and were prescribed Fertomid. I took the pills as prescribed and we had intercourse as instructed by the doctor. I tested myself yesterday morning and the ovulaton test showed positive. I tested myself again this morning and the test was negative. Can I be pregnant or is there something else going on? I am also experiancing cramps. Doesovulation stops imediatly after conception?