sudden onset of bradycardia/arrhythmia question

My boyfriend, 60 years old, with no history of cardiac problems, recently had a bout of the flu (May, 2008).  Following this, his heart rate would fluctuate with readings as low as 40, and even at one time 39.

He has no history of arrhythmias, and his heart rate prior to getting sick would, with normal activity, would average 75-90 beats per minute (bpm).  He regularly tracked it because he is trying to lose weight.  He is currently overweight.

He wore a Holter monitor for 24 hours and the cardiologist that reviewed the results said it indicated possible 3 blockages, and stated that during sleep his heart rate would dip to 20 bpm.

The doctor also said that my bf would probably need a pacemaker.

When I heard this I wondered how such a sudden onset of arrhythmia could occur?  I knew what his heart sounded like before the flew, and I have lived with him for 8 years.  I mean, I lay with my head on this wonderful man's chest every night, and I would hear the steady sound of his heart.  I NEVER heard anything like the sounds I hear now from time to time.  

It kept hitting me that something doesn't make sense:  before flu - no heart irregularities.  After the flu, weird palpitations.

I discovered by google flu and bradycardia, and flu and arrhythmia that there is something called myocarditis.  His cardiologist mentioned nothing about this.

In addition, the doctor, when asked by Doug (bf) about activity levels, was told, "Well, I wouldn't operate any heavy machinery."  But nothing specific about rest.  

I have read a lot about myocarditis, and I am convinced this is a possibility.  Doug has agreed it could be, because he matches a classic profile that show up in the articles.

Doug is scheduled for a echocardiogram on 6/2.  Will this assist in any diagnosis of myocarditis?  And shouldn't the cardiologist have been more adamant about total rest (which I read, in mild cases, is all that is needed for the inflammation to resolve)?  And, in addition, shouldn't there be some sort of possibility of medications that can assist (anti-inflammatories) that would be low-risk but might mitigate the time of healing?

AND (sorry about this long post) should Doug get an immediate second opinion?  Because from what I read, myocarditis can have a great prognosis if treated quickly.

Thank you - I am very grateful for any reply.