PMS symptoms, no period and severe nausea????

I’ve been having really bad PMS for two weeks where I’m emotional, fatigued, SUPER crampy and I FEEL like I want to start my period but it hasn’t come! I’m on day 60 and still no period! Like I feel so much pain down below and it’s really annoying especially when I’m in class.

I’m also always feeling super sick as of a week ago. Everyday i wake up fine but then I feel extremely nauseated when i drink or eat anything. I don’t believe it’s a chance of pregnancy, I had sex three weeks ago but we used protection. Could it be maybe an STD? Is it my PCOS flaring up? Can I go to an urgent care to be checked since my doctors is closed?