Need help??

[Haych]

My chain snapped last week so I ordered a replacement and fitted it. I tightened the chain it had a bit of slack and the bike ran smooth for a few days until yesterday. I was just looking over the bike after parking it and I tugged on the chain and noticed the whole left side of the swing arm was moving about and the bolt on the right side was sticking out a lot. I’m confused how it’s happened and what’s wrong with it now and how to fix it. Could it be because my chain was maybe too tight? It ran fine for a few days I’m not sure. Can someone help thanks.