How to deal with diarrhea caused by calcium supplementation for a two-month-old baby?

Patient's question:

Sky
Detailed medical history and consultation purpose: The child has a calcium deficiency and has experienced diarrhea (a significant increase in bowel movements) after taking Zinc-Calcium Special Oral Liquid.
Why does the child still have diarrhea symptoms even when the mother takes calcium supplements and breastfeeds?
Please help me: I want to know how to supplement calcium for an infant in a safe and effective way.
Previous diagnosis and treatment history and effectiveness: Calcium deficiency

Doctor's answer:

Hello, how to supplement calcium for children?
Children are in the period of growth and development, requiring a larger amount of calcium than adults, so it is important to supplement calcium in a timely manner to prevent calcium deficiency. When it comes to proper calcium supplementation, the following points should be noted.
(1) Whether a child is deficient in calcium should be determined by a doctor, not self-diagnosed.
(2) Healthy children with normal diets and well-balanced meals do not need additional calcium supplements.
(3) Calcium deficiency in children can show obvious symptoms within the first two months of birth, such as night crying, excessive sweating, reduced appetite, increased susceptibility to respiratory infections, anemia, and baldness on the back of the head. In severe cases, it may lead to tetany in the hands and feet. In such situations, calcium supplements should be used for treatment.
(4) When taking calcium supplements, they should be combined with vitamin D-containing medications, such as cod liver oil, as they can promote calcium and phosphorus absorption, reduce urinary phosphorus excretion, and increase blood citrate levels. Citrate combines with calcium to form a high-concentration complex, which is beneficial for the calcification of new bones. However, it should be noted that vitamin D should not be taken in excess, as it may lead to persistent hypercalcemia, followed by calcium salt deposition in various organs and tissues, impairing their function. In severe cases, it may affect intellectual development.
(5) During calcium supplementation, children should avoid eating spinach and dairy products, as spinach contains oxalates that easily form calcium oxalate precipitates. Additionally, taking calcium supplements with dairy products may cause curdling, both of which can affect absorption.