Are birth control side effects similar to pregnancy symptoms?

My boyfriend and I were using the withdrawal method for birth control (I know that its not very effective) and I decided it was time to go on the pill. I had a pregnancy test before I started the pill, but I was told it would only indicate pregnancy that occurred at least 3 weeks prior. It was negative. I was supposed to wait to start the pill until the sunday after my period started. My period was late so I waited to start it..until I ended up in the ER with severe lower abdominal pain. They did a blood pregnancy test and it was negative so I figured it was safe to start the pill and that my cycle was just a little wonky. I am 7 days into the pill and feel awful. I have stomach/back pain, heartburn, headache, sore throat, fatigue and overall just feel crappy. We still had unprotected(withdrawal) sex even though I had just started the pill. He has issues with sensation when using condoms. Any insight into whether these are pregnancy symptoms or birth control side effects would be wonderful. Thank you!