Feels like I’m about to have a full mental breakdown😭

I’ve been feeling so burned out for the last weeks.. I just found out yesterday that I had an exam last week that I didn’t even know about.. I’m behind on everything, I called in sick at work today cause I just feel like I’m about to break. I tried to call my doctor but she’s not at work until next week. Tried to call my therapist but she was busy, and on top of that I’m having constant flashbacks and my mind is racing, my heart is pounding, I’m nauseous and dizzy. I don’t know what to do 😭