14mo screaming on/off in duscomfort...

Li

My little boy has been crying/screeching on and off this afternoon in obvious discomfort.... it’ll stop after a bit and he’ll be ok then start up again and he’s grabbing his nappy and arching/tensing. Does this sound like constipation/tummy ache??? He’s my first and he’s never had anything like it before so I’m not sure what to do....