Thank you for clarifying,
The fact that it is happening with solids and liquids suggests that it is a problem with motility (meaning the contractions) of the esophagus.
This can be due to esophageal spasms (which is exactly how you have described it). These can be triggered by acid reflux, hot or cold foods, carbonated beverages and even certain smells.
The underlying cause of the spasms is not well understood.
I do recommend that he consider having a swallow study or an upper endoscopy (scope) performed to evaluate his swallow mechanism and to make sure there is not any underlying obstruction (unlikely due to the fact that it is so intermittent).
Treatments can include medications....however given the infrequency his doctor may elect to simply watch for now.
Here is more information if you would like to read:http://www.mayoclinic.com/health/esophageal-spasms/DS00763
Feel free to ask any follow up questions you may have,
If you are satisfied with my help, please remember to click accept.