2000 Subaru Outback Check Engine Light, Sputtering Engine

So my car started vibrating and making these rumbling sounds. I was scared, so I quickly drove home (not far) and parked it. The check engine light was flashing and then the oil light went on. When I checked the oil, it was almost completely gone.

I purchased some new oil (a blend) and filled my car. It runs more smoothly now, but the engine is still sputtering. The check engine light is on when I start the car and it starts to blink shortly after. Could my car have been damaged from not having enough oil? Is it something else? How can I fix it?

To more specifically explain what my engine is doing, it makes a soft thudding noise and vibrates. I opened the hood and looked at the engine, and it seems like it's shaking a lot. I can see a belt in there which is running, alternating between running slower and running faster. I went around to the tailpipe and heard the same sputtering come out of it as well.

Please help. I'm too poor to afford a large repair cost and I don't think I could drive it to a shop anyways. Thanks.