Even if they did refer to season 7 and the headaches, Blake wasn't even with Krystle at that time, as he was in jail, and told Krystle to go see a doctor when her dizzy spells began (after the accident). And if Blake had known about the "illness" all the way back to/from season 2, with the miscarriage, how come he wasn't frantic when Krystle first of all had an accident and blows to the head (serious or not) and then began feeling dizzy and weak? Blake would naturally think of the illness lying dormant in her body and realize he had to get out and take her to a doctor without her finding out too much about the real condition. The doctor Krystle went to for her spells after the accident could just have easily revealed Blake's big secret and told her; Oh I'm sorry, but you have a massive tumor in your head. Or the doctors at the hospital when she came in after Michael and Blake pulled her out. Blake missed to inform them about a dormant plate-monster in her head. This was somewhat dishonest writing and usage of the Dynasty-saga's history.