We have an 18 month old new construction home with a large septic tank (upgraded for disposal but have not added it yet). Yesterday my son’s,whose bathroom is on 2nd floor, toilet got stopped up (no tp just Urine) it took quite a bit of force to get it to go down and when we were trying we heard the other toilet on the 2nd floor gurgle. Also, his shower would not drain. First floor toilets are fine.
Any thoughts?

Ps. We do intend on calling a plumber but it’s Sunday and I’m a bit nervous.