Back pain

I would recommend deadlift, of course with weights you choose. It can help prevent injuries by increasing the strength of your muscles around critical tendons and ligaments. Supporting joints with strong muscles is crucial to preventing injury, especially in the lower back.

I would not recommend any type of weight lifting without first consulting a physician. If an injury is the cause of the pain, you could make it much worse.

Gentle stretching is often a good choice, in the beginning. Heat can help relax sore muscles, but if heat is painful stop using it. Sometimes, ice is better though, to relieve pain as well as inflammation.

Well of course he needs to consult a doctor but he asked for advice so this is just my opinion :)