Brief Answer:
I would like to add Azithromycin and salbutamol

Detailed Answer:
Hello

Thanks for asking on this platform

I would like to know
1)If there was any fever in the beginning?
2)Does cough get worsened in morning/night?
3)Is there any vomiting following excessive cough?
4)Is there any breathing difficulty or noisy breath?

The most common cause of upper respiratory tract infection in this age is atypical bacterial infection.
Macrolide group of antibiotic(like azithromycin) has a very good coverage for these atypical organisms.
Dimetapp contains Brompheniramine(an antiallergic)and pseudoephedrine(a decongestant).Both these ingredients helps in relieving cough and cold.But as symptom is persisting I would like to add Salbutamol(a bronchodilator)for better relief.
You have also mentioned that there are mosquito bites over the legs and arms.I request you to attach an image so that I would better able to differentiate from other conditions with similar lesions.
I wont get worried if there is no breathing difficulty,child is active and accepting feeds well.
I would suggest you to consult a pediatrician to discuss the need of azithromycin and salbutamol.

Please let me know if you have any more queries.
Wishing for your child's speedy recovery.
Regards

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