Hi, I m a 33 yr old female, 117 lbs, and have been on antibiotics for about 1 1/2 weeks due to a sinus infection and bladder infection- I still feel very bad. I feel weak, my heart is beating irregularly, having hard time breathing comfortably, and I have upper back pain and muscle spasms. I feel like an idiot going back to the doctor AGAIN, but I almost feel like I m going to pass out.