I have been feeling stress, yesterday my neck was tense I cracked it. Couple hours later I have red spot in the white area of eye. What is it?

Red spot in eye. Sometimes a blood vessel in white part of eye beaks & makes a red spot (hemorrhage) that looks bad but usually isn't. Most resolve without tx. If pain accompanied the spot, see dr/eye specialist.
Subconj heme. Your description sounds like a subconjunctival hemorrhage which is a small area of bleeding on the white of the eye. This should resolve in 1-2 weeks and is unrelated to your neck cracking. If you develop other associated symptoms, see your eye doctor.