First we are sorry to hear your horse may have a physical issue. We strong urge you to contact your vet as soon as possible.
Your horse may have a history, be older or other situation that could cause your horse to look ill-regular aka “off” or “lame”. Judges only have one basis, what they “see”. Based on their well trained experience, they can only go by that visual. It is the judges job to report these observations, just as they would in a physical horse show. In a location based show aka physical, the whistle would have been blown, you and your horse asked to come to the judge’s booth, given an explanation and excused from continuing.
For online shows, it is the same. Whatever the experience of the Judge says about how your horse is going, is final.