How to find out why electric usage has more than doubled?
What is your heat source?  I had a rental house that had a heat pump that failed and the renters complained about a sudden spike in electrical billings.  BC the heat pump failed, the house was being heated with backup electrical resistance elements.
The most common cause of a spike in electrical usage is space heating.   Also, if you have a leaking hot water faucet (or other leak in a hot water pipe) it could cause the water heater to run much more than normal (assuming an electric water heater).