Mercury Amalgam poisoning is a chronic condition. It does not start with a cracked tooth. If you were fine 4 weeks ago than it is not Amalgam poisoning.
On the other hand if you have had these problems since they put the mercury in your mouth than it may be mercury poisoning. Blood tests dont normally show or look for mercury poisoning.
# of amalgams?,
years in place?
consumption of fish?
consumption of aluminum?