About My Pitbull/Bull-Mastiff That's 51-2y/o Please Help Me Out It Would Be Much Appreciated!!! Thank You?

I have a 5 1/2 y/o Pitbull/Bull-Mastiff and I've noticed when I was cleaning the yard hate to sound gross but theirs a few LIQUID piles instead of the regular solids and I had my window open in the kitchen and heard him YUP - like he was in pain so I went outside and he was SCRUNTED UP like a regular dog would to take a "****" and was strugglin and crying with liquid's comin out and his stomach feels kinda HARD like he's constipated and was wondering if their was something I could give him to help him go maybe something to turn his "Hershey Squirts" into a solid and help him go better maybe soften it up cau