I have been having a terrible pain on my right side of my next after streching too hard since 3 -4 weeks ago. What is the cause and what can I use?

Torn muscle +. You may torn a muscle or hurt one of the joints in the neck. If warm compresses and a non-steroidal pain medication, e.g., Ibuprofen does not relieve it within 2-3 days you should consult a physician.
Many reasons. When you strech to hard you tesr a mucsule fiber orsprian a joint , please check out with your doctor.