what is failing?

I am having a problem in my home and may need to re plumb my sewer hook ups with the city. The problem is that whenever I drain a lot of water or use a lot of toilet paper i get back flow. If you try to force the water down with a plunger it comes back up in other showers etc. I know its under the problem is in the yard because we have roto rooted the sewer pipe before and it would stay working for a while. We have a massive pine tree in the front yard that apparantly has broken into the sewer line. :wall: None of this responsibility falls on the city right? I need to hire a plumber or re plumb the line myself I assume. Any help as to how I should go about doing this if I decide to do it myself?

First, the history: We bought a house last spring. The water worked fine, however the well pump did seem to kick on more frequently than it ought to. We had water nonetheless up until the pump quit working about 2-3 weeks ago. We called the guy we bought the house from as we were supposed to have a 1 year warranty. He had his fix-it guy (not a professional plumber) come out and install a new pump and bladder tank. We had water for a very short amount of time. We called the guy and he came back out, re-primed and we were back in working order. Well we thought so. The pump would run and we wouldn't get water. I kept re-priming it (now that I knew how from watching him and reading up on it) and we had water for an hour or two after, but that's about as long as it lasted. My wife then called a plumber friend of a friend who drove out and looked it over. He said it needed a check valve and that should fix it. I bought and installed a check valve. The water worked yay! Well it worked for about 24 hours then the same problem. Pump runs, no water. I unplugged it a bit and checked the prime. Was still full of water so I plugged it back in and it worked again... for about 24 hours, then it happened again. I talked to an engineer I work with and he recommended installing a pressure gauge to see if the leak was on the effluent or influent side of the pump. I did that and the pressure held just fine until we used water (We didn't use water for 2 hours or so after installing the gauge). So I called my plumber friend back home and asked him if I should try pulling the pipe and looking for a leak. He said I might as well, so I started tugging when I got home from work last night and it was in the ground pretty tight. I started digging some to see if it was cased or not. I found that it wasn't and as I kept digging I got to a bend. I thought that was strange so I kept digging. Lo and behold I found a check valve so I kept digging with my two boys (7 and 6 yrs. old) help. We found another bend and finally the pvc was tied into a metal pipe which mysteriously disappeared under the dining room of our house which was an addition to the original house. Conclusion: It appears that when the addition was added they rerouted the well piping over to a new location and now we're sucking air somewhere along the line or either the pump is having a hard time sucking water through all those bends and piping (4 - 90 degree bends between the well and the pump and I'd say 6-10 ft. of 1" piping). The old pump sat on the ground and pulled water through it even though it ran more often that it should. The new pump is atop the bladder tank. Question or otherwise desperate plea for advice: 1.) Is the problem a leak or is the pump just too far from the well and too many bends and pipe in between? 2.) Would moving the pump to the ground, and possibly closer to the well fix the problem? Should I do that? 3.) If I did that should I move the bladder tank with it or would it be ok where it is? 4.) Or should I just call a plumber or well company to come have a look and fix it all the while plunging into the depths of debt? We need to get this fixed fast as we have 4 kids, a pile of dirty dishes, a mountain of dirty clothes and we're pretty much broke, at least until payday. Your help is much appreciated.:) The new pump is a Flotec Shallow Well Jet Pump FP 4012-10.