The injury capped a miserable evening for the Hammers as they suffered a 5-1 defeat against Arsenal at the Emirates, despite taking a first-half lead.
Potts, 18, whose father, former West Ham great Steve, was born in the United States, was involved in a clash of heads in the second half and it is believed was knocked out immediately before crashing to the floor. Although he did speak to medical staff, the youngster’s answers did not make sense.
“Hopefully it is concussion and nothing more than that," Allardyce told reporters. "He had not regained consciousness by the time he was stretched off. The clash of heads initially knocked him out and he hit the floor as a dead weight and I think that is what the problem was. He hadn't spoken when he came off the field. He spoke about some things that they asked him on the pitch but they were not the correct answers so that is how we knew he was concussed. He was communicating but was obviously confused.
"He is in observation tonight but you don't know with these things, only X-rays will tell if anything else is wrong, but hopefully it is just concussion. We will do everything in our power to make sure he has a quick recovery."