What Causes Pain In The Penis After Urination?

Hey there. I am a little worried and was hoping to get some ideas of what might be wrong with me. About 7 or 8 days ago I noticed a severe pain in my penis when I was just about finished urinating. The urine was normal until after I felt the pain. The last few dribbles were bloody. I dealt with the pain but after 3 days I could not stand it. I went to the doctor and she said it looks like a UTI. She also had my urine tested for STDs. Haven t heard back yet. She also put me on Cipro and after 4 days it has gotten worse. The pain is unbearable when I urinate from start to finish, there are little clumpy stringy things that come out when I urinate and instead of a little blood at the end dribble it is a stream of blood and urine from about halfway through urinating to the very end. Happens every time I urinate. Also, the constant feeling of needing to urinate is making me insane. Any thoughts or input would be greatly appreciated. Thanks.