By constipated, do you mean their butts look like they are clogged with dried poop? This is called "pasty butt" and needs immediate attention! Using Qtips or a soft cloth and warm water with a tiny bit of baby shampoo or dawn dish soap, moisten the poop. Then work it carefully between your fingers to crush the bits, and more water/Qtip to remove the bits. Do NOT pull it off, or you risk tearing skin! Gently dab them dry and put back in the brooder. You must clean them up, and re-check them every day. They will outgrow it in a week or two.
Check the temperature in your brooder. Pasty butt is most often caused by being too hot. It can also be caused by the chicks ingesting hard-to-digest substances (wood chips? seeds?) other than their chick feed or soft foods like yogurt or scrambled eggs. You can supply some fine sandy grit, or "chick grit', to help their digestion.