My 7 month old baby is not ill since he was 3 months old he won't have a day sleep and wakes up frequently at night and cries all day i'm so stressed?

Crying baby: At 7 months my first consideration would be teething. If he is not teething i would be concerned about milk or food intolerence.For teething you can have your child chomp on cold things, like a half of a frozen bagel.For milk intolerence determination add lactaid tablets to child's formula and see his response.In the end you should discuss the problem with your doctor.