Leflunomide side effects

Hi everyone. Recently got confirmation that I have AS (wasn't a surprise to me my dad had it so) was on Salazopyrin and methotrexate for two years and recently my Rheumatologist changed my meds to Lunar and Entiflam or something like that due to the medication messing my serotonin levels. I have been using Lunar for 3 months and the last month and a half i have had diarrhea that just doesn't want to clear up. Been on antibiotics, did stool samples, seen two doctors and nothing comes up as wrong. Last possible explanation is the Lunar medication in my mind. Have any of you had any experience with Leflunomide and its side effects?