I have a HTML structure that we cannot change as it is generated.

I need to look for a specific img src, I need the original src as a val, and also then replace the src with our own custom one.

The structure looks like this:

<span id="edit5_WMFStream">
   <div>
      <img src="...">
   </div>
</span>

I want to look for the span id ending with WMFStream, and I have nothing to id the nested div and then img. Have tried several things but so far can't even get to select the div, letalone the img then src.