Leaking

I noticed for the last couple days I've been having some dampness In my underwear. It has an Oder to it. I'm 18 weeks pregnant and lastnight I went to the bathroom then had to go again after. Nothing's dropping down my leg or anything like that, I have some pelvic pressure this morning and a few drops of thin wet fluid in my underwear. Wondering if it's just urine? Should I call my OB?