Earlier This Week (Sunday) Had To Go To The Emergency

Earlier this week (Sunday) had to go to the emergency because of imbalance, sweating and chest pain.
Stayed overnight for observation but after tests and a stress test they found nothing with my heart. On Tuesday went to a meeting as I was coming home the imbalance started coming on again. When I got home I not only felt the imbalance but nausea and felt pain in my neck. Particularly on my back, right side of my spine bone between the shoulder, up. When I massaged it the imbalance and nausea started to decrease. What is happening - what could be the problem?