Is it normal for a child to have increased thirst and urination?

Hi doctor,

My son (4.3 years old, 46 pounds, 3.5 feet), seems to have a tendency of increased thirst and urination for the past two months. Can I request you to review the below summary and attached reports to help him get well? There are at least three to four occasions in the past two months when he had drunk up to 4 to 5 quarts of fluid in a day and urinated at least an hour up to three to four times an hour in the evening. These days he also seemed to have some amount of sweating and hiccups too. A couple of these occasions happened the next day after he has taken some outside food (like noodles). However, there was no loose motion or fever as such.

When he urinates three to four times in an hour, the urine volume is not that much always, and neither there was any color or smell. We have also tested his urine routine twice, but nothing obvious was there (attached). We have taken him to a local doctor a couple of times, who did not find anything wrong clinically. His blood pressure comes up as 90/60 and 88/60, while an instant sugar check (after 1.5 hours of light breakfast) shows 132.

He had reported three to four occasions of a headache and reeling of the head in the past two months or so. He did have some forehead injury (not a fall) three months ago, which was reviewed by a doctor with antibiotics and the local dressing was done. He has taken two doses of Zentel syrup (one tea spoon) three months back. He has got two instances of cold, cough, and fever in the past two months, for which he had taken medicines like Calpol 250 mg (1.5 teaspoon), Xyzal (0.7 teaspoon, Montec LC Kid (0.8 teaspoon), Ambrolite-S (one teaspoon) and Lupita (0.6 teaspoon) since almost past one month.

Apart from the above symptoms, he seems to have had moderate stomach pain (around the naval chord) since today morning along with a vomiting tendency and no appetite. We have given him Domestal Syrup (1.2 teaspoon) twice, which although prevented vomiting, but he seems too tired, weak, and unable to do his daily routine, etc.

Thank you doctor,

I request your help to clarify a few follow up queries as below.

1. As we stay in a hot and humid place, we developed him the habit of drinking more water. He, in normal conditions, drinks up to 3 quarts of water in a day. Is this fine from a medical perspective?

2. He had been on a dosage of Arbivit 3 Forte drop since childhood, which is increased to 0.02 fl oz due to frequent cold or a cough since past 7 to 8 months. Should he continue that? Or, is it recommended taking this only during winter?

3. He has been taking flu vaccine once in a year. Should it be stopped after he reaches five years?