“No action for the recovery of damages upon a claim against a health-care provider for personal injury, including personal injury which results in death, arising out of medical negligence shall be brought after the expiration of 2 years from the date upon which such injury occurred.” However, “in the event of personal injury the occurrence of which, during such period of 2 years, was unknown to and could not in the exercise of reasonable diligence have been discovered by the injured person, such action may be brought prior to the expiration of 3 years from the date upon which such injury occurred, and not thereafter” In addition, a plaintiff may toll this statute for 90 days with a notice of intent to investigate. [DC § 6856]