Re: Do you think I have roundworm? Help!

I also think you have roundworms. The lung filling up with fluid happens at a later stage though, you must have been infected for quite a while. The are very common and are transmitted very easily. Many of us have them since we were kids. They can be silently in your lungs and digestive tract without causing much trouble. Once the immune system crashes, problems start.
If you really don't know what to do, why not go back to the vet who treated the dog. Vets know parasites quite well. The doctor who prescribed the Antibiotics is a fool who should be hanged. You can follow the same drug schedule the dog has got, except you need to take them much longer.
You can also try to do enemas, they are a good start to get a clue of what you might be infected with.
You can look up different protocols here as well, ICU, mattk3 posted these. You need to be on systemic meds for at least a year to get better. Start now so you can reduce further problems that might develop afterwards if left untreated.