How Can Bladder And Urethral Pain With Painful Incomplete Voiding Be Treated?

hi, for the past five months ive been having bladder and urethral pain. i had a urine infection 5 months ago but the pain never went away after the infection cleared up. my doctor thought it migyt have been thrush which i had 2 lots of treatmants for and it still was sore so i got an abdominal scanwhich showed i wasnt voiding all my urine (300mls left after voiding) and now for the past 3 weeks ive developed flank right sided and back pain that also goes slightly round my front. I saw a surgeon on thursday who was going to perform a cystoscopy and following a routine urine test prior to the procedure it came back with epithelial cells +++ and red cells in it. He told me now that the pain ive been experiencing in my bladder and urethra for the past five months and now with the right sided pain has been from stones and sediment in my kidneys and has decided not to carry out the cystoscopy! so now im back to sqaure one, pain AFTER i pee and constant side pain. surely if it was stones this would have been picked up on my scan and it doesnt explian why im not voiding all my urine? im drinking heaps and the urethral buring does subside eventually by doing this but its been going on so long im at my wits end now, as is my poor husband.. Can i also add that during my period my pelvic bone hurts really bad and when i get really bad uretharal burning theres lots of mucus in my urine. im concerened about the epithelial cells. should i get a second opnion or be satisfied with the surgeons? thanks rebecca