No action to recover damages for injury to the person, or to real or personal property, caused by negligence, or by reckless or wanton misconduct, or by malpractice of a physician, surgeon, dentist, podiatrist, chiropractor, hospital or sanatorium, shall be brought but within two years from the date when the injury is first sustained or discovered or in the exercise of reasonable care should have been discovered, and except that no such action may be brought more than three years from the date of the act or omission complained of, except that a counterclaim may be interposed in any such action any time before the pleadings in such action are finally closed.