Sewage coming up the shower drain

We ran a 55 foot snake through the shower drain. And removed the toilet to snake it through that drain. At our wits end on what else to try. Called the city and they took off the manhole cover and said everything looks good. The city guy thinks there is a clog from the upstairs toilet to the main drain. That doesn't make sense to me. But I am not an expert. We can't run the shower, dishwasher or wash machine. It will fill up that shower in no time.
Plumber can't get here until tomorrow if it all. Plumber said 400 would be the minimum this will cost.
We are a bit rural and it's really hard to find anyone to come out this way.

Any help would be appreciated.