The summer is over, so foreign workers aren't needed (in summer, Montenegro takes up to 70000 of them), so all caffe/restaurant jobs are taken by local workers. Even if you're exceptionally better than local guys - you don't speak Serbian, so your chances getting job there are none.
But, since the summer is over, construction of buildings can continue (it stops during summer, so the noise doesn't disturb guests) and since you're up for a hard work, you should try seeking such jobs. Again, knowing the language is a +
The accommodation is usually given by the company where you work (they probably cut the income for that)
I'm the kind of young people who just like guests WHO PAY and I can give you accommodation in Petrovac, Montenegro 