When I do laundry the smell of the septic tank comes out in bathroom shower drain. Also toiletbowl goes dry.

When I do laundry the smell of the septic tank comes out in bathroom shower drain. Also toiletbowl goes dry.
Well! We know where the smell's coming from. Now let me tell you what causes it. You have vents that are blocked. The bathroom lavatory roof vent for sure and most likely the washer roof vent as well.
Let me explain. Your washer discharges with great force causing a suction in the system.
Normally this would be relieved by the washer vent but if it's blocked it seeks relief else where, in this case the bathroom roof vent. If that's blocked also the suction will attempt to vent through a fixtures trap pulling the water seal out.
The solution would be to have the vents checked and cleared. Good luck, Tom