Until you can trace down what is draining it, I recommend one of these, totally worth having, it will keep your battery from going dead, still keep a jump box on hand just in case.
That comes with connectors that can be attached to the ground that the car battery runs to, and also the 12v lead.
Or you can just use the alligator clips it comes with, it is so small you can put it under the hood, just be sure motor is cool before doing so.
I have leave my cars anti theft system off though, because occasionally the alarm is set off while having this attached to the car, no idea why it does that.
The most common causes of parasitic drain are under hood lights, trunk lights, headlights or glove box lights that do not turn off when the door is closed. Relay switches that are stuck in the "on" position can also cause a battery to drain.
Also a bad charging system can cause the drains, as well as bad diodes on an alternator, a good diode lets current flow into out of the alternator, and into the battery only, a bad diode can let the current flow the other way, so it can drain overnight.
When doing the tests for drain, if your radio or antitheft system requires you to input a code after the power is interrupted, better find it before you start. It'* likely that you'll need it.
If you need it and can't find it there should be a number we can find for you to call, provided it is a factory AC Delco radio...
And thanks, I am happy to be able to help in any way I can, let us know how things go, I hope you find/fix the issue soon!