Right NowThe Thyroid is what could be of issue. It's being monitored. I say treat it, treat it now during the season. Cardio vascular has also come up and a bunch of other things. Doc says he doesn't want to go on a "fishing expidition". It may be time!
Even when I was swimming it was strength and form that made the performance. I had quick energy - good for the 100 weak in the 200. My training ability was much weaker than anyone that I ever trained with. I was very motivated but it appeared as though I was lazy. So this is not new.