Baby cries for milk all the time

Are you sure he really is hungry? Check his diaper. Maybe he is uncomfortable because he wants to burp. Maybe he just is sleepy and grouchy. Maybe he just wants some attention from you.
Do you have enough milk? Check by squeezing the brown flat area of your nipple, gently pushing inwards. If some milk comes out than you can still feed him from that breast. If not, let him try the other breast.
Remember that the let down reflex after which your milk flows readily takes some time. You need to be relaxed in order to let the milk flow easily. Take it easy. Check out our tips for total breastfeeding
Maybe you need to take in more fluid. Drink a lot of water, soup, fruit juices. You need a lot of fluid to produce milk for your child
Try traditional foods that are reputed to increase milk flow. Eat lots of fish. Try some fish at every meal. It does help milk production. Long beans are said to help too.
At worst, give you baby some formula milk. Drink lots of water after that and try to express out as much milk as possible an hour later. This is to help stimulate your flow of breast milk. The more milk you express, the more milk you have.