Fever- 103. 3°f. And dosage per day?

My father started to have chills last night and developed fever. This morning his temperature was 99.4°f and had few sporadic and transient episodes of very mild headache. Today in the afternoon he has developed high fever of 103.3°f and feels severe weakness, fan is off but he still feels slightly cold. We haven't taken his corona test as this maybe a viral flu too, I intend to have his Covid-19 test taken if symptoms turn serious like breathing difficulty, chest pain, confusion etc. Consulted a doctor near our locality, he prescribed  Dolo-650 and Biotax-0 200 CD twice a day, I have given him one dose for the day. He's feeling better now. What should I do for now? What otc flu medicines should I give him? Besides other medicines I think it would be better if he took some vitamin c and zinc tablets. Could you please suggest some vitamin c and zinc tablets with their strength and dosage per day? It would be of huge help. Thanking in advance to our corona warriors-our doctors :)