Unfortunately it can take some time to resolve.
He can apply a heat pack to the area. You can gently massage his back, shoulders and neck to relieve any muscle spasms.
He can use paracetamol for pain relief. If he does use or the doctor prescribes anti-inflammatory medicines like Ibuprofen, ensure that these are taken after food, - sometimes the doctor may prescribe a stomach remedy like Omeprazole to protect the stomach. Anti-inflammatory medications do not suit everyone and can also cause stomach bleeding.
The doctor can also prescribe, or you can purchase the creams, gels or sprays for muscle problems.
I presume your husband had an xray to rule out any bone problem. Thoracic bone problems can cause spams that can feel like a heart attack.
Tell your husband not to do any lifting or anything physical to allow things to heal. When he does start to lift things again in the future, stress that he if a load is heavy or awkward he will require help from another person. He should keep his back straight and bend his knees to lift anything off a lower level. Twisting whilst trying to lift can put stress on the back and can cause back problems.
If the condition does not settle after a few weeks, ask the doctor for a referral to the Triage service for physiotherapy.
If you are suffering from back and neck pain for quite some time, consider going to a massage expert or chiropractor. It is recommended to seek a professional chiropractor to address your issues before the pain becomes unbearable.