I was like this for the first few days, just take your ibuprofen and paracetamol regularly that should help. I basically stayed in one place all day for the first few days but I got up to get a drink etc and the walk did actually help. As for sitting up try not to use your arms to push yourself or anything, I grabbed the covers on my bed and pulled myself up that way or used my legs. After the first few days the tightness wears off loads don’t worry!