Uncertainty

So I think my Betta fish is dying...all it does is float around. There's no filter or anything so I've been changing the water every three days or so. I recently put it in a larger tank, probably about 3/4 a gallon compared to the tiny jar he came in. I am nowhere near a pet store so there's no way for me to get medicines to treat him either. My goldfish died two days ago, so I'm wondering if it's somehow connected. Though they were in separate tanks, I used the same water for them when I changed the water. Perhaps it wasn't completely distilled and therefore it was really really bad for them? Idk..Well he just sits on the bottom of the tank now, kinda sitting there, or floats up to get water. He hasn't eaten in two days. I thought this morning maybe it was because he couldn't find the food in the larger tank but now I'm sure it's something more. I have set water aside so that I can change it tomorrow and hopefully he'll be getting better soon. The only thing I'm worried about is that he seems more pale, the ins are all clumped together. It looks like he's trying to breathe, even when he's under water, and he can't seem to stay upright. There's a white patch near his stomach, but it doesn't seem to match up with anything I've found online. Honestly, I'm not too upset, because how attached can you really grow to a fish that will die in a couple of years? I think I'm done with fish though. I've learned my lesson and I know I can't handle the responsibility of taking care of something so delicate. I'm just worried that this will somehow reflect on how well I take care of animals ...or...children in the future. Life is such a delicate thing that is very balanced. If anything, at least Yuji taught me this. The next time I write, he may be floating around in the campus sewers somewhere.