hypertrophic obstructive cardiomyopathy diagnosed with it but now they are not sure

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to give a quick background. I am 39 years old, and  was training for an ironman triathlon and had my regular 2 year cardio appt. 3 and a half weeks ago (I see a cardiologist every 2 years due to a family history of heart problems, but none with hcm). At the appt. I did an ekg, which was fine, and a stress echo. after the stress echo my cardio. said that I had IHSS, my pressure gradient during the test was high (200) and they said I had a 7mm obstruction on my septum, then I had a cardio M.R.I. done which confirmed the same thing but this time (it was 3 days later) my obstuction was at 4mm (since the M.R.I. I am told is much more sensitive and can get better readings), they did see some reguratation back thru the mitro valve during the m.r.i.  My doctor asked me to stop training after the test and put me on 200mg of toprol xl 100 in the morning and 100 in the evening. (i had been taking 50 mg per day for pre hypertension). Fast forward to this week, went back in for another stressecho test to see how things were, my pressure gradient came in at 44, there wasn't any reguratation back thru the mitro valve, and the septum obstruction was at most 2mm now. the doctor that read the stress echo, informed my doctor that I did not have IHSS. My doctor has allowed me back to moderate training but no where near the level that I was at before. my question is 1) could I have athletes heart and the break from training reduced the obstruction, 2) was it the dosage of toprol, 3) am I just one lucky person. I would love to get back into my training and still have time to do the race but they are being very conservative with me right now. Should I go and see another cardiologist and have them test me again?

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1) I did not have any symptoms
2) the high dosage of torpol that I was put on I think was done more for my desire to continue to workout some and my doctor knowing that it would be hard for me not to push it and he wants me to keep my hr at below 130 during workouts (i use to run at about 155 bpm during long (13 to 15 mile) runs