Bubbling toilet

I have a basement toilet, that was probably installed by the last owner. I have live here for 6 years. I have noticed ocasionally the toilet bubbles. Also, I've had some problem recently where the shower was running upstairs and the bubbling happened, so I flushed the toilet because it looked like it was going to overflow. MISTAKE. Crap water went on the floor. It was crazy, I wished I could have shut a valve. So I called Roto-Rooter, They removed the toilet, and snaked all the way to the street sewer pipe. He said it should be all set. But it happened again. Now everytime someone flushes the toilet or takes a shower, I cringed when I here the toilet bubble.

What is the problem and what can I do to fix it?

My house has three bathrooms above this toilet in the basement. I also had an addition, which added another bathroom to the system.

This is indicative of a blocked main drain line. They may or may not have done a good job snaking the line. Also, it's possible that either when put in, or sometime after, the slope is wrong - you could have it running flat without the proper slope, or it could actually have a section that tries to go back uphill. If you have either of those two things, it is easy for it to clog up again. A properly working sewer line slopes all the way from the last thing dumping into it all the way to the town sewer system line.

You may also have a break in the line, and if you do, sand, dirt, rocks, roots, etc. could quickly fill it back in after a cleanout. Some of that should have been obvious to the worker doing the job, but some of them aren't trained all that well. Often, not always, you'll get better luck with someone smaller that doesn't have to pay all the national franchise fees. You may want to consider having someone come in and run a camera down the line...that can often tell you if there's standing water, roots, breaks, etc. Once you find the problem, then you can figure out a solution. It's not aways cheap. The camera fee often isn't alot, but that varies from vendor to vendor as is their skill at interpreting what they're seeing.