Stiffness

My friends baby is six months old the same age as mine except her son never relaxes. I’m talking this kid is as stiff as a board 24/7 fists always balled up during feeding sleeping doing anything. Has anyone experienced anything like this? His next checkups isn’t for another three weeks and my husband and I brought it up to her and she googled why and it showed a lot of things no one wants to hear and hoping maybe it’s the same for maybe it’s more common than we realize.