I have cholecystitis, had IV antibiotics in hosp and am on antibiotics at home. Today urine was cola colour. Should I b worried?

Yes. Bile duct issue. Given your recent history of cholecystitis, gallstones are a concern. First, did they remove your gallbladder already? Also, do they know if gallstones caused your cholecystitis? Occasionally, gallstones from the gallbladder can slip down into your bile ducts. Once stuck in the bile ducts, bile (in the form of bilirubin) can build up in your blood, appearing as dark colored urine. Call your MD.
Yes. Yes urine that has a cola color can signal liver diseases.See a physician to evaluate causes of dark color urine.