Why does a two month old child cry so much?

Q: My wife gave birth to a male child 1.5 month ago, by operation and subsequently she underwent family planning operation also. The child is doing fine and till date is on mother's milk. But the baby is crying throughout the night. He wants to be fed all the time and searches for the nipple every now and then. His birth weight was 3.54 Kgs and after 40 days his weight is 4.25 Kg. The doctor may please advise me whether we can give him some other food (formula 1 or something)? The other question is when can I have sex with my wife after these two surgeries?

A:1. At 40 days your child has gained adequate weight. Weight in all babies decreases for 3-5 days and is regained by 10 days, so actually it is weight gain in last 30 days only. If the baby is passing urine 5-8 times and stool daily, do not worry. Tell your wife to take plenty of fluids and increase her diet, just more of all food items. Most babies will be awake at night when parents want to sleep. Normal pattern of night sleep is established by 3-4 months age. The baby should be fed as frequently as he demands and mothers milk is the best food for small babies.2. The partners can have sex 6 weeks after normal delivery and 3 months after operative delivery.