You are fortunate to experience such physical signs on your body. If Paath is done according to Gurmat i.e. with concentration, love and faith, then Gurbani moves the mind from the physical towards the subtle i.e. towards Aatma and Vaheguru.
Tears in the eyes are the sign that Gurbani is making an impact on you. They are a sure sign of love for Guru Sahib.
Feeling light weighted is indicating that you are getting away from the physical world into the Andithi Duniya i.e. towards Vaheguru.
By feeling fever, I am assuming that your body temperature is rising a bit from the normal and this too is a positive sign indicating that you are getting energized by Gurbani.
Shivering in the spine is also a sign that Gurbani is making an impact on you. When Bau Mal Singh jee and Colonel Piara Singh jee first started doing Naam Abhyaas together, Bau jee told Colonel jee after few days that his lower spine was shivering while doing Abhyaas. I think such reactions from the body indicate the feeling of Vismaad while indulging in Gurbani Paath and Naam Abhyaas.
Guru Sahib's Kirpa is surely there on you. I hope you will continue to get Guru Sahib's Kirpa by indulging in Gurbani with increased vigour.
Kulbir Singh