"Stress" Test

The idea seemed simple enough, have me run on a treadmill and have it exhaust me until my heart rate reached 90% of my max.  This stress test was the final attempt to carefully examine my heart under duress in hopes of finding a cause for my lightheadedness and fainting episode earlier in the year.  The only problem was that the treadmill maxed out before I did.  I was 25 minutes over my allotted time and the treadmill setting could not go any faster or incline any higher, and the doctor made the decision to stop me at 84% of my max.  He said he had sufficient information to conclude that my heart looks fine and that my episodes might have been due to dehydration.  How many of us endurance athletes have had similar situations when we go to the doctor because such tests are designed for the average, more sedentary person.  This whole week has been about self-doubt and uncertainty.  Coming off the biopsy, I'm trying to recover but at the same time, feel the pressure to race well this weekend. I probably rode too far (75 miles) and too hard (racing and dropping a group of guys off my wheel during a hill climb) on Sunday, my first day back.   I followed it up with a 30 minute run and 3000 yard swim.  Monday  was a 10 mile run and a 4000 yard swim.   Tuesday was a brick and today was a hard 4000 yard swim and track workout in two hours.  I did convince myself not to do weights this week and to cut back on the intensity until today's swim and track workout.  I'm sure all this falls under the unhealthy competitiveness category.  It's just swimming, biking, and running--I can't be doing too much damage can I?