I am having bad pain and tightness on the right side of my neck.

Neck strain: You have probably sustained a neck sprain or spasm. You could take some anti inflammatories to see if it helps relieve the pain. If you have associated fevers or vomiting, this could be something more sinister such as meningitis. If you cannot recall any injury to the neck, go and see your doctor yo endure it's nothing serious.

You need to be seen: If this is so tight that it causes pain and makes your head go into the wrong position, something is seriously wrong. At your age it could well be a reaction to medicine called dystonic reaction, or something called torticollis but either way you need some relief which can be obtained only after a diagnosis is made. Then it can often be relieved quickly. Good luck.