That's pretty easy to figure out by looking at the graph of your rating over the last 90 days and then checking the archive.

Looking at the graph, it's pretty obvious something bad happened to your rating in several spots-- particularly at the end of May.
It looks like you timed out on four games on May 27th and 28th.
It looks like you finished about 108 games over the 90 day period. With a 5% timeout ratio, there is another one somewhere. I looked at the games at the end of July (another downturn) but those seemed to be normal losses.
I'm sure you can find it.
How can I find out the dates when I lost to Timeout? I ask, because I am puzzled by my Timeout percentage over the last 90 days.