I Have No Heartburn, But I've Been Having What Feels

I have no heartburn, but I've been having what feels like spasms in the area between my breasts, in what I believe is the esophagus. The spasms are extremely uncomfortable. I've had these from time to time, but over the past three days it's been constant and becoming less tolerable as time progresses. Also, a lot of pressure in that area. What could this be?