Welcome to the forum.
Chest and neck pain
seems to be due to muscular spasm. Bad posture might be the cause.
Medical drugs like pain killers - acetaminophen/ibuprofen
and muscle relaxants might be helpful.
Cervical isometric exercises are beneficial to maintain the strength of the neck muscles. Neck and upper back stretching exercises, as well as light aerobic activities, also are recommended under the guidance of a physical therapist.
Hot fomentation helps in relieving acute symptoms.
You can avoid using a pillow.
I also encourage you to consult an orthopedician for both evaluation and to avail stronger prescription medications (if over the counter medications are not helpful)
I hope this information has been both informative and helpful for you.