Need advice

I have a almost 2 week old baby. For reasons I dont feel like talking about...decided to give him colostrum the first few days and then switch to formula. He ended up getting constipated a few days ago, so I hand expressed milk for him. I gave him about an ounce of breastmilk a couple times each day to help him poop. His poop came out green. I know that means that he's not getting a balance of hind/fore milk...but can it hurt him? The breast milk was given in addition to the formula he already received. So I essentially just used the breastmilk as a laxative for him. Please don't try to persuade me to breastfeed, I just want to know that the additional breastmilk won't harm him. The green poop threw me off.