Cardiac back Stress Syndrome although self-resolving can be very painful in its acute stage. It will mimic the classic back pain and even trigger sciatic leg pain. If one happens to have a chronic low-back condition, this will certainly trigger a major flare-up.
~ The terminology is descriptive of the cause ...meaning ~
During emotionally stressful events, the body will attempt to disperse the stress physiologically.. The most common pathway is the organs and in particular the digestive system, i.e. stomach. Everyone has commonly experienced this.
Approximately 35% of the time it chooses a different pathway - the Heart. The heart does not appreciate the new stressor and will let you know. You will begin to notice low back tightness traversing horizontally across the low back. Additional symptom often will include chest/heart sensitivity and upper back tightness, a generalized aching in the arm/shoulder more commonly left than right, and a weak feeling in the legs (hamstrings). This condition can quickly progress resulting in an acute inflammatory reaction and substantial back pain.
Remember without a precipatory back injury/incident, tendons ligaments and muscles were not torn or strained so you will recover quickly.
What can you do about it (besides an urgent office visit) is heed to the back pain and lie down, rest, take an anti-inflammatory agent (optional), acknowledge the source of the stress, take 24-48 hours off and use whatever resources one has to diffuse the emotional stressors.
You will get better but remember not to take the stress with you to bed via phone calls, emails etc. - REST.