Pregnant after finishing Prostap ?

Hi, I was on 4 months of Prostap injections after surgery to remove endo from my ovary. Had my last injection 26Nov which lasts 28 days. On the 27th & 28th Dec I had a little bleeding, more like spotting. Had unprotected sex 29dec. Since then I have had crampy pains like af, my boobs have been sore on and off, I feel lightheaded when I stand up suddenly, I'm usually wrapped up like a bear but have been so hot and keep getting really hot on my face and neck. 2 days ago I had a browny pink discharge when I wiped then nothing and had a smear on my pants today but nothing when I wiped. I now have a stringing clear/white discharge inside and I got a blob of it when I wiped. Could I have ovulated the 27th & 28th and now be pregnant. Took a test today (would be 4wks preg) and it was negative.