I have big problems in my old house. Started with kitchen sink not draining, so I plunged. It finally went down and ended up in my bathtub. now the toliet is either overflowing or yuck comes up in the bathtub. I have a septic tank. I tried using a utility pump and drained alot of water out of it. Still having the problem. House is over fifty years old. Pipes are cast iron. When I use my sink or toliet it rains water from a trap in the basement. HELP.