Thanks for your query.
You have noticed reduction in semen volume since recently after an episode of fever
The decrease in volume of the semen is mainly due to less intake of water and may be due to frequent ejaculation either by masturbation
or sexual intercourse.over a short period of time.
Following measure will help you to increase semen volume
1) Practice regular exercise for 45 minutes followed by meditation
for 1/2 an hour in the morning.
2) Take high protein diet rich in vegetables and fruits and Vitamin A
3)Take anti oxidants like Almonds 5-6 everyday..
4) Avoid alcohol and smoking
5) Drink more water 3-4 litres per day.