Cold packs v. Heat packs for back and neck pain?

I’ve always thought that heat was the best thing for aches and pains but I’m currently trying cold packs. I have a lavender wheat bag which I recently discovered can be used cold as well as hot by putting it in the freezer!

Anyhow, currently have chronic neck and back pain, which I think is caused by stress and general bodily tensions. I’ve tried exercising, which just made the pain worse.

ANYWAY! What are your experiences? Are cold packs better than hot packs? Are they more useful for certain types of injury? What’s the science behind them both? My doctor just said it depends on the person… but I’m not convinced that this is entirely scientific!