Brief Answer:
Maintain adequate hydration and observe

Detailed Answer:
Hello

Thanks for asking on this platform

I can understand your concern.
I would like to know if there is history of cough and cold along with the fever.
The most common cause of fever with loose stool is viral infection.But blood in stool is suggestive of bacterial not viral infection.
Here I suggest you to give him plenty of fluids (ORS)to avoid dehydration.Give zinc drops for early recovery from loose stool.
Monitor temperature and give antipyretic like paracetamol to bring down the temperature. Meanwhile continue giving antibiotic as it will take care of bacterial infection if any.
Observe the stool pattern and also if the blood mixed stool persists or baby gets lethargic,fever continues, if urinary frequency gets decreased or oral acceptance is poor consult your pediatrician.

I hope this helps.
Please let me know if you have any queries.
Regards

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Brief Answer:
Monitor temperature,Investigations may be needed if fever persists

Detailed Answer:
Thanks for follow up

Small ball like swelling in neck is most likely enlarged lymph node secondary to some throat infection as said by your doctor.
In most of the cases fever responds to antibiotic within 72 hours.
I suggest you to monitor the temperature to see the pattern of fever.If fever spike's frequency or severity persists in the same pattern for next two days,I would suggest you to get blood workup(Complete blood count and CRP) done to see any bacterial infection.If investigation is suggestive of bacterial infection,antibiotics may need to be upgraded.
I would suggest you to observe him for next 24-48 hours and if fever persists or condition gets worsened consult your doctor.Meanwhile give plenty of fluids to avoid dehydration.Also give some probiotic to maintain the gut flora(It also helps in recovery from antibiotic associated diarrhea).

I shall be glad to answer if you have any more doubts.
Wishing for your child's speedy recovery.
Regards

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