What Causes Acute Abdominal Pain On The Left Side And Bleeding?

Hi,
On the 16th I did two pregnancy tests both positive, the next day i did another positive again. I was getting mild period like pains which were more concentrated on my left side but heard that period like pains were normal. On Sunday 22nd i woke up and i had been bleeding, not a huge amount but not just a spot. I got an emergency appointment at the doctors who did two urine tests and one blood test which were all negative and said that based on my blood test i could not have been pregnant in the last two weeks although there is a very small chance i could have had an early miscarriage, I worked out i would have been 6 weeks on Monday. I have not had any real pain or heavy bleeding and now it is just a little pink tinge to my wee. However the pain in my left side has got worse and i can now feel it from my front to my back. Can you advise me if the blood test could have been wrong? Was it a miscarriage? Why am i still getting pain in my left side and why has it got worse? Thank-you