Constipated baby! Need opinions. (TMI Picture)

Chelsea
Riley is 2 months old today, and she switched to formula from being EBF at about 5 weeks (doctor suggested the switch and suggested a formula - similac total comfort). Until yesterday, she didn't poop for 3 1/2-4 days and I didn't think too much of it because it's apparently not super uncommon for babies. Because all her previous poops had always been once a day and normal since the switch. However, when she finally did poop, she was definitely constipated. I had to take her diaper and open it so she was free to poop because she was crying. It was like little dark green cheese curls. Any suggestions on how to help her feel bett? Should I call the doctor or is she just figuring her digestive system out?