Cahill is having a CT scan on the injury, with the FA expected to announce the results on Sunday.
Hodgson is crossing his fingers the results are positive.
However, his initial worry after Cahill was shoved into goalkeeper Joe Hart by Dries Mertens during the early stages of Saturday's 1-0 win over Belgium at Wembley was that the Chelsea man was in trouble.
"I wasn't too happy about it (the challenge). 'Unfortunate' is too kind a word," Hodgson said.
"When a striker is chasing a defender who is feeding a ball to the goalkeeper, those nudges and pushes take the defender into the goalkeeper.
"It is something if you have been a goalkeeper you take very unkindly to.
"The referee gave him a yellow card, which he deserved. Unfortunately for us, the consequences might be a lot more than a yellow card because a fracture is a distinct possibility."