Infection?? So worried :(

Erin
Okay so without tmi I had all the symptoms of cystitis. I took the 48 hour treatment from the chemist and drank no sugar cranberry juice and lots of water. How ever it's made no difference. I'm now getting really bad pains on my left side/back and abdomen now. What could this be?? I'm 2 weeks past af and done so many ovulation tests but all came back completely blank. Could this all be linked? I'm so worried somethings wrong as I had a really bad misscaraige in August and lost lots of blood that I needed a transfusion. I'm making an emergency app at the gp first thing in the morning was just wondering if anyone has any idea or been in my situation. Thanks