Im Having A Burning Sensation When Urinating， Left Lower Abdominal

Im having a burning sensation when urinating， left lower abdominal pain aggravated when moving or bending for 2 days, i have pcos already delayed for 1 1/2 months had pt for 3 times, last pt was just this morning and all came out negative, sexually active.. Had brown spotting for 1 week last week.. Is this uti? Or a more serious problem?