What did i do and how do i stop the neck pain? i "cracked" my neck and now have pain when tilting head up/back and rotating to the left.

Try: Neck pain can be painful and alarming. Cracking the neck can stretch soft tissues and rarely cause fractures unless severe force was used. As long as your arms, legs work you could try icing or heating the area try ibuprofen and if no better get checked at an emergency or urgent care facility,

See good chiro: Leave the cracking to professionals. You may have caused a mild fixation or muscular trigger point. This is usually easily foxed with proper manipulation and soft tissue care.