Help with my septic system?

Ok so let me start here, we just purchased our house 2 months ago and about 2weeks ago the city was out doing work on the main water lines they gave us a notice saying that we may experience difficulties with our water, well now all of our drains are barely draining but the toilet flush's fine. Then when i woke up this morning the tub had what looked like poop in it like in splatters though like the drain exploded a little..sounds gross i know but then coming out of the drain there was a lot of hair and not from our heads im guess the previous owners...is our septic full or could it be from the city?