to slightly restate Bill's Questions...
How old is the wheel with the broken spoke?
About how many miles has the wheel been ridden?
What side is the broken spoke on?
Have all the broken spokes been on one side of the wheel?
Did the spoke break at the hub/J bend or somewhere else?
What is the approximate timespan between the three broken spokes?
proper advice will be only a guess without the answers to these important questions.