Help structural issues with the house, Maybe

[u/GeneFew7282]

So I was tearing up flooring by my back steps because there was some water damage and I wanted to lay new flooring well upon doing so I discovered there was some crossmember or 2 x 4 that was just broken rotten and split so I started ripping up the sub flooring and found what looks like rafters that are pulling away from the supporting truss included our pictures cause somebody please tell me what’s going on here and how I can fix it. Remember this picture is into the floor by my back door and down into the basement and this building is very old. Do next to those boards is the basement steps descending and directly below is wide open air basement. What can be done if anything and what the hell is happening is part of my house sinking or am I missing something here?