I have a blood value for creatinine kinase of 298 u/l. Is that unhealthy or is it normal when doing workouts a few times a week?

Creatinine kinase. This is okay as long as you don't have severe pain. Ck is considered significant when the value is 10 times upper limit of normal.
You're healthy. In a dysfunctional health care system that requires physicians to practice defensive medicine, you may be forced to get an ekg or some other cardiac stuff to prove you're not having a heart attack. This is perfectly normal for a guy who works out -- in fact, it's average "in my series" for someone who strength-trains.