We had a 5 day electric outage this week, No plumbing issues before the outage. During outage, still used the toilet(pouring water into the tank to flush)
After power came back on (the next morning) I started a load of wash, during spin cycle, toilet and tub started bubbling and over flowing.
Thought it was a clog, so I went online and found a remedy that said use baking soda and vinegar. This did get some stuff out, then snaked both the toilet and the washer drain to be sure.
Thought it was fixed. This was the 25th ( 2 days ago) today, no issues with the washer, but was using the up stairs shower and heard this bubbling, from the same toilet. (not the tub) but didn't over flow this time. Not sure if any of this is related to the electric outage and maybe my pipes were frozen? Please advise...

So it sounds like you are on a well, correct?

Yes. Well and septic.

Does your septic gravity feed to the tank and field or is there a booster pump?

The septic gravity feeds to the tank. We don't have a booster pump.

You need to call a septic guy. Your tank is overfilled or the line from the house to the tank is blocked. Once you get oursidee of your house septic problems are for the pros, sorry