Newborn constipation

Holy cow is all I can say. 

My LO is 3 weeks and 6 days and seriously struggling to poo! He strains and grunt and fusses all night and day just to get a little bit out, not to mention it's always hard and sticky instead of soft. He struggles to burp to the point we have to stop and burp almost every half ounce. 

This has been going on since he was 2 weeks and 1 day. We went to his doctor due to blood in his stool and he said LO had a small fissure, and recommended switching formulas to Enfamil reguline. That worked for almost a day then he said do Newborn Mylicon, and that helped some for a few feedings. Now we are trying Gripe water and apple juice per doctors orders and he just still seems in pain! It is seriously breaking my heart and I am just stuck. I hate seeming him struggle like this. 

Earlier today he had horrible diarrhea, and I had to change him due to it running up his back. As I was changing it he projectile pooed all over and I had to bathe him. I'm just at a loss. Has anyone had this happen? What helped? I just can't stand seeing my little bundle like this anymore.