Plz help me!

[b][i]Can someone out there plz help me! I am 15 years of age and yes unfortunatly I have had sex. For the past almost 6 months now I have been throwing up really bad and have had some pretty bad headaches along with backpain. I went to the E.R about 4 weeks ago cause my nausea was getting so much that I couldn’t bare it! When I went into the hospital and was waiting to be seen I was contantly urinating every 5 minutes or so. The doctors did a urine test and a blood test and they said both came up negative for pregnancy. But as many people around this area knows we have one of the worst hospitals around and they aren’t very good with patients and I know there lab was very backed up that night! They said they did run the blood work which was kind of hard to believe cause of the fact that not to long after they drew the blood a guy from X-Ray came to take me down to get some x-rays. Well I told the x-ray guy they was running a pregnancy test on me and but still he did an x-ray on my stomach and nothing showed on x-ray. The doctors here couldn’t come up with no explanation for why I have been feeling like this so they gave me a reason of a bladder infection and sent me home. Now the question I have is could I still Be pregnant? And when I left that hospital I believed the doctor and went home and put on my birth control patch and have had it on for 4 weeks now! Could that harm an un-born child? while it does sound wierd I have been gaining excessive wait through the past couple of months and I have no explanation for it! Could someone please help me with these questions cause it would really be appreciated cause I really dont know anymore!!! Thanks a bunch! :S