16w5d nausea is still here

I felt so good the last few days but now i do not know what happened. I am so so so so nauseous and my head hurts like hell. I had a cerclage a few days ago amd since then i am on bed rest. Maybe it is the lack of fresh air. Now i am wondering,how do contractions feel like?sometimes i fell like my heart is beating in my uterus. And i have mild lower back pains. Am i just too paranoid?