Marc,
Use this week as an unstructured recovery week. Do not do any running this week but consider doing some short 15-20 min walks no earlier than Wednesday. Swimming is a great recovery exercise as is very light spinning on the bike. Do only what you feel like doing and keep any workouts to less than 30 min at lev 1.
This is what my coach included in my original training plan as the post IM week workout. I can see why this was his advice. I rode to work yesterday with Mike. Not pleasant. I had absolutely no wind at all. My legs felt great but I couldn't breathe.