Is it permissible to avail oneself of the concession (rukhsa) regarding the continuous discharge of secretions during the ovulation period, and what should one do concerning a prayer one has already performed while in that state?

If the discharge stops for a sufficient time to perform Wudu and prayer, it is not considered سلس (incontinence). If you verify the presence of discharge before the prayer, your prayer is invalid and must be repeated, as it is among the things that nullify Wudu. However, if you doubt whether it occurred before or after the prayer, it is presumed to have occurred after the prayer, and your prayer is valid in that case.