Frequent urination. This and am scared.

My 18 month baby girl is 10 kg. She had UTI last month and had antibiotics. But last few days i have observed she is doing lot of urine frequently. In 30 min or 1 hour. Night sleep is also disturb. Her night diaper is extremely wet. She is having same amount of liquid input but urine output is so much increased. Urine is transperant white no smell. My i read on internet they say it's polyuria and have some dangerous causes. I am really scared. Please help. Her appetite is also little reduced and she is having softer stool these days. Initially she used to urinate every 2-3 hours. When she had uti she urinated frequently but in small amount unlike now the amount of urine is large. I read about kidney problem, diabetes, etc. as cause of this and am scared.