Hmm, If they are able to still flush and thier water doesn't backup into your place then you need to have your pipe snaked from you unit to the septic. now if they can't flush thier toilets because they will backup someplace or overflow then it could either be the septic or a common drain line plugged.
WEll we had the septic people come out yesterday.
and our problem is solved.
The entire septic pipe line under the house leading to the septic was clogged up.Of course they did not charge me for it. They said it looked as though it has been from years and years of build up with what looked like powder detergents and grease. It just finally could not get anything else through it.. They snaked the pipe all the way to the septic and now everything is flowing fine.. Thanks for everything.