Ulster physio Gareth Robinson explained: "Paddy had to be helped from the field last Friday having sustained an neck injury.
"However X-rays and a CT scan have come back clear, though he has been left with a stiff and painful neck and back that will require physio and ongoing assessment."
Backs Paul Marshall and Jamie Smith, who played 60 minutes between them against Bath, have also been receiving treatment.
"Paul sustained an injury to the AC joint in his shoulder, but X-rays taken on Monday were clear and he will have ongoing physio treatment," added Robinson.
The remaining injuries in the Ulster camp relate to McAllister's front row colleagues, Declan Fitzpatrick and Bryan Young.
Robinson confirmed that Fitzpatrick suffered a back spasm during the Ravenhill encounter, but is 'already on the mend' thanks to physio treatment.
Meanwhile, the Ireland-capped Young, who was a late withdrawal from the side to face Bath, is due to return to training on Tuesday.
"Bryan picked up a hip injury in training last week. He is responding well to physio and rehab and is expected to train with the squad this Tuesday."
Brian McLaughlin will get a second pre-season chance to run the rule over his players when they visit the Stoop this Saturday to play Harlequins (kick-off 2.30pm).