What the hell was that?!

25, Male, 6ft 2, 210lbs. Smoker, UK, No Prev. Conditions or Medication.

Woke up with a slight running nose and cough, within the hour I was shivering under the blanket with a worryingly high fever, extreme muscle pains and spasms, inability to get warm for several hours despite the fever and dropping in and out for conciousness. Felt honestly touch and go, I wanted to tell my partner to call an ambulance I felt so horrendous, but I didnt have the energy to talk or signal her, she just fed me painkillers and water bless her. Worst I have ever felt in my entire life and I have had some close calls, especially with the heavy spinning nausea kicking in throughout the day. I'm feeling rough this morning but I got out of bed with little pain and was able to eat something. What the hell happened for me to be coming around now so soon?! Cause for concern?