Vomiting, Fever and Headache can be a symptom of pregnancy. But I don't think diarrhoea is a symptom of pregnancy. Another indication that you are pregnant is when you miss your periods. You can confirm your pregnancy by using a pregnancy kit like Predicte Pregnancy Test Kit or U-Check pregnancy test kit. Take the test using the first urine sample when you wake up in the morning.

Vomiting, fever

I think you should see a doctor asap.
Also, I think this weather is bad and maybe carrying wipes with you in the bag, and make sure to clean your hands before eating.