14/3 feeding itself?

I know enough about electrical to get by, but I am far from an expert. I tried to place a GFCI outlet outside instead of the standard receptacle that is there since I bought the place. It tripped immediately after connecting the load side. I started tracing the connection but so far I haven't been able to pinpoint the issue. I did find this though, and I'm stumped. It's a 14/3 run that is powering its own black on a switch. The red wire is pig tailed and connected to switch. The black wire of the same run is connected to the other side of the switch. I have no idea where this cable comes from, or where it goes. Everything that I can determine in line with it is fed by 14/2. I don't notice anything being powered by that switch when on. I have no idea where the run is connected either, because the outlet right below it is 14/2 (same circuit) and the outdoor outlet and light fixture on the other side are also both 14/2. I'm absolutely stumped. The shoddy jumpers and the backwards wired 3 way (which I fixed the 3 way) tells me it was a rush job whoever did it to begin with.

Yes, I've called an electrician. "This week" has been over 3 weeks now, and the second one I called never got back to me. I plan to call a third this week but I'm wondering if anyone has an answer what might be going on here.

I know enough about electrical to get by, but I am far from an expert. I tried to place a GFCI outlet outside instead of the standard receptacle that is there since I bought the place. It tripped immediately after connecting the load side. I started tracing the connection but so far I haven't been able to pinpoint the issue. I did find this though, and I'm stumped. It's a 14/3 run that is powering its own black on a switch. The red wire is pig tailed and connected to switch. The black wire of the same run is connected to the other side of the switch. I have no idea where this cable comes from, or where it goes. Everything that I can determine in line with it is fed by 14/2. I don't notice anything being powered by that switch when on. I have no idea where the run is connected either, because the outlet right below it is 14/2 (same circuit) and the outdoor outlet and light fixture on the other side are also both 14/2. I'm absolutely stumped. The shoddy jumpers and the backwards wired 3 way (which I fixed the 3 way) tells me it was a rush job whoever did it to begin with.

Yes, I've called an electrician. "This week" has been over 3 weeks now, and the second one I called never got back to me. I plan to call a third this week but I'm wondering if anyone has an answer what might be going on here.