Hello,
If you had dengue fever 15 days back and since now everything is settled but still the effect of that viral fever is there then you don't have to worry. Believe me since I myself has been through this.. You will have bodyache and generalised weakness for few days.
Nothing special you have to do just take multivitamin tablet, good food, fruits that's it.
You will be fine soon.
Hope this might be helpful to you.
Health Tips
Keep good hydration. Drink at least 2-3 liters of liquid.