How to express: a narrator is narrating an event in the past, and wants to describe an event 2 years before that In English this is very easy to express, but I'm struggling to express it in Chinese. I've asked multiple natives and they are all struggling with this (much to everyone's surprise).

Basically, you have the following situation: a story with a narrator explaining some events in the past. The events are happening during some time during the narrators high school years. The narrator at one point wants to explain the equivalent of: "Two years before I had gotten a bad sickness, which is why I drank so much water."

We have all sort of thought up the following:

在那之前的两年……


but the problem with this is that in Chinese if you use this it's unclear whether the event was 2 years before, or sometime during those 2 years. It's a duration, not a specific time.

Is there any way to express "2 points before some ambiguous time"? I don't want to have to resort to absolute times for everything. Thank you for your help!
In my opinion,


  
  在［那事］之前的兩年……
  在［那事］的前兩年……
  


both mean during the two years before［那事］. Compare


  
  在［那事］之後的兩年……
  在［那事］的後兩年……
  
  
  During the two years (immediately) after［那事］


I suggest


  在［發生Ｘ］的兩年前， 。。。。。。
  
  Two years before X happened, ...




Another technique, which is perhaps not strictly the answer you're looking for, is to make the context very clear in a printed book. Specifically, an occasional first-person narrative should be actually using a different font, akin to English novels sometimes using italics.


  
  
  Excerpt from a digital edition of 紅樓夢 from 國立臺灣大學中文系 (source). The main body of the text is in Song/Ming Typeface, while direct quotes are given in a regular script typeface.


I believe this is why it is difficult for native speakers to answer your query. Printed books may employ the following font styles for different parts of the text:


Song/Ming typeface for the main body;
Regular script typeface for quotes, or a short segment indicating first-person narratives;
Imitation Song typeface for annotations.


In your case, all that's needed for clarification is to print the narration in regular script, and simply write “兩年之前，。。。。。。”.