Do I have food poisoning or am I pregnant??

Hey pals!! I'm sooper worried right now and am looking for support.

I had sex with my partner around five days ago, and today I've had severe nausea accompanied with vomiting and diarrhoea. I'm very much dehydrated and feel quite week. I lost about 1 kg in the process. Also, I feel like I have a heightened sense of smell. The very next day after the vomiting episodes (sixth day after sex), the nausea has disappeared completely and I feel perfectly fine now.

Can someone tell me if what I've been through was a pregnancy symptom or food poisoning from something I had eaten that day?

Also, I don't wanna get pregnant. Can I use penorit to prevent it right away?