Bill....been there done that many times. Hate to say it, but you probably need a new tire to keep you from having more flats. I have had flats and checked my tire over and over and over, and still flat.

 

Been personally with some cycling friends having the same problem...they bought a new tire too.

 

Gotta make sure the tape around the inside of your wheel is good too, so a spoke is not poking through....but imagine you would have seen that

Thanks Tim.  Good points.  If I don't find anything obvious I will definitely get a new tire.  That's a small price to pay as opposed to multiple flat tubes and lost workouts.  Time's a wasting and I need to pick up my game here soon or my upcoming Oly Tri is going to be a training day.

Bill