Thank you for your query and Welcome to HCM community.
It seems that your baby has got Flu or Common cold
resulting from most probable seasonal viral Upper Respiratory Tract
Infection. Fever & cough can persist upto 2 weeks and you don't need to be worried. Fever can fluctuate over the course.Paracetamol
is more safer than Mefenamic acid
(Meftal-p). Mefenamic acid can worsen respiratory difficulty, so advised to avoid in child who have breathing difficulty. It can also cause various gastric problems like irritation, ulceration, bleeding etc. So, you better avoid it and stick to P-125.
Frizium can prevent Febrile convulsion, so it's use may be useful. Azithromycin
is antibiotic and works against bacteria. Cough syrup has debatable role.
Your mentioned current treatment is fine and No further investigations needed.
Hope, this helps. Wish a quick recovery to your baby.