I just bought a house last summer. The house is a little over 100 years old. Since the cold temperatures started I started to see problems with the floor drain in the basement. First I was doing laundry and I saw some bubbles coming up. No big deal. The next thing I know half of my basement is flooded with all the laundry water. I called the City Sewer and they came and drained the sewer from the outside of the home. This seemed to solve the overflow problem for a while. That is when I started notice a really bad smell coming out of the sewer. I figured there must be a clog so I put draino down. Perhaps this was a bad idea because the first time I ran the washer after the draino I saw the overflow of water from the drain again. I called the City Drain and they did their thing again from the outside.

Note that this is an old home and the floor rain is rusted quite a bit.

What should be my next step?

First is to figure out why you have a back up that is ongoing. Have you ever tried cleaning out the pipes? You could have root damage. It's a easy and cheap fix and if you can take the line all way to the sewer then that's even better. Also you need to check for venting. Make sure your plumbing ( drain lines ) are vented properly.

It's not the smell that's your biggest concern. It's those roots the city keep auguring out in the city raiser out in the curb. To see if I'm correct. Call the city and ask how far out from the cleanout did they run the snake. And what came back on it.
Then get back to me far a solution.
Regards Tom