Hello. Thanks for writing to HCM. This does seem like a viral infection. However, since it has been 5 days since the fever started and he still has quite severe symptoms (most viral illnesses start waning by the 3rd day), he might need some blood tests like a complete blood count atleast. Certain viral fevers like Dengue may cause decrease in the platelets which needs to be monitored. If the level falls below a certain value or he developed rashes or bleeding anywhere, platelet transfusion may be needed. Also, maintain his hydration well as high fevers are known to cause dehydration which may in turn worsen his illness. Hope this helps. Wishing him a speedy recovery. Regards, Dr Geeta