Pms or Implantation. Stinging pain!

Hi I'm 25yrs. Old. I have irregular periods On december i have started taken a slimming coffee also on January ihave started exercising and lose bout 6-7kgfast . Last month my expected period should have started on jan.17,2017but didn't came instead i had brown discharge for two days on the 18th or 19th of January but most of the time i have brown discharge before having or my period is near. But on the 21nd of January i had unprotected sex using the pull out method. On December 2016 i had my period around dec.9-13 from what i remembered. On jan.22 i have taken a antihistamine tab called virlix for 3 day since i had rashes and can't control the itch after 2 days i went to our local dermatologist to have my skin checked then i have very dry skin and gave me antihistamine tabs loratadine have to drink it for 2 times a day for 4 days. wondering if the antihistamine has anything to do with my clycle.have been experiencing cramps on my left ovary mostly also sharp stinging pain