Long story short I hurt my knee pretty bad the other day while playing football. I can barely stand on it let alone work product/put up a truck. I can't exactly afford to go to a doctor just for a doctor's note... I just need to stay off t for amother day or so... how do I go about explaining that?
Explain it exactly how you explained it here. Just be honest. Depending on what type of manager you have, there shouldn't be a problem. See if you can switch up with another employee for the days you can't come in. Don't force yourself to work if you physically can't do it. Avoid further injury if you can help it. Kroger will still run things without you.
Do what I do, lots of pain killers (maxing out at the bottle limit), ice it, and if you can get others to do your tasks then do it. I have never been able to lift more than 30 lbs but I don't tell management. I use team lifting or make others lift the items.