"Sinking feeling", lol

Kitchen sink stopped up, both sides.  One has a disposal, that clogged first, when unclogged it comes up in the other side....  Shower drain retains some water also....   Thinking it's either one huge veggie clog or....time to empty the septic tank....  Both are new occurrences.   Have tried a plunger in the kitchen.  Debating about trying an auger....  Have opened the outside trap, water flows freely to the septic, so that is good.  Calling plumbers....they want $80 no matter what and time includes trip time.....