Renter P trap problem

Can someone assist with this issue please.

I am renting a house in Southern California. I noticed that everytime I flush the down stairs toilet the homemade shower addition makes a gurggles noise, and you hear the water running under the shower pipe. I am not sure if there is a p trap. Lately there is also a foul smell in same bathroom. Can someome tell me if I am supposed to hear the toilet water running directly under the shower drain ? If so, can this cause the smell. Someone ( not a plumber) tells me that there may be no p trap and that this is necessary to keep the fumes out.

Mike

It could also be that it is incorrectly vented and the water is pulled out of the trap every time the toilet is flushed. Either way, it would allow sewer gas into the house and be a source of the smell.

If this shower is not used the trap may have dried out by evaporation. Run some water and see if that cures it. If not there may not be a trap. Discuss this problem with the landlord if running water doesn't fix it. Any repairs would need his blessing!

In a correctly installed shower p-trap, if you take a flashlight, you should be able to see a circle of water at the top of the trap. It could be down a few inches to maybe as much as a foot.