Leak under the shower

[MattInAR]

I had water coming in the master bedroom from outside and in order to be sure where the leak was, and how bad the moisture problem was I got a moisture meter. Turns out the leak didn't do much damage and I only have to replace a small section of subfloor.
However I didn't leave well eough alond and decided to check the ajoining wall to the bathroom where 2 years ago there had been a leak from the shower faucet since repaired.
I have major moisture in the wall and subfloor there. I checked the facet and shower head lines and there is no water leaking on those connections.
The water seems to be coming from under the shower.
This is a one piece plastic shower with no cracks in a 2002 shultz doublewide.
I believe its from the drain connection as this is an inside wall.
Is there anyway to fix this without having to pull the shower out? Will I have to rip off the belly board?
I can't get a plumber to come out, no one around here will work on mobile homes.
Thanks

[MattInAR]

Pardon the typos, it has been a long day.
All I wanted to do when I started this two weeks ago was replace the cat peed on carpet.

[JD]

If this is a drain/ P-trap leak, you should be able to fix it from underneath. You will have to open up the underbelly material to get to it. A faucet or pipe leak can usually be repaired through an access panel on or made on the wall behind the shower. Sometimes the water heater is in the way from the back side.

JD