Had the septic tank pumped in August, 2 months ago, but I am still having the same problem. The showers back up, the toilets fill up and bubble, and the sinks back up. What is the problem and what can I do that isn't costly? Cost me a few hundred dollars to have the septic tank pumped and it didn't even fix the problem...

1. did it fix the problem temp ?
2. Have you looked at the clean out to see if the septic is indeed full ?

3. if the septic is full, then the drain field most likely has a problem, perhaps blocked, went bad or other field issues.
Was the septic inspected when they pumped it, or just pumped ?

When it was pumped it fixed it for a few weeks but there is no way it is already full. Haven't looked to actually see if it was full, don't really know how to look. When it was pumped they did not inspect it at all. I have been reading a lot of different threads and saw that it could possibly be a clog in the main line. Is this possible?

You must first localize your problem. Locate the septic tank and open up one of the two inspection ports. If the tank is full then you have a saturated drain field that can no longer disperse the liquid the septic tank sends it The solution would be to move the drainfield. However,
If the septic is not full and backing up you have a blockage in the line from the house to the tank. The solution would be to snake the line.
I hate to say this but it looks to me like you have a bad drainfield. If that's the case get three estimates and go with the one you
're most comfortable with, Good luck, Tom