I have been on Diovan 160mg for a little over two years. (A genetic predisposition to HBP has 5 out of 7 of us in the family on medication for the condition, even though we exhibit none of the other risk factors. SNARL!) I only started cycling just over a year ago, so I can't provide any insight in that department. But, I can tell you that the first week was horrible -- dizzy, nauseous, light-headed, couldn't even manage to string five words together to form a coherent sentence. Really threw me for a loop.
The second week was much better, but I had absolutely no energy. After that things improved drastically. My only problem was remembering to take my meds every day.
On the positive side, my frequent headaches disappeared -- to be expected when you're no longer trying to function with a dangerously high bp of 190/120. And, unlike other classes of bp meds, Diovan does not lower the ceiling on max heart rate, if you happen to train with a heart rate monitor.
Please note, you are not supposed to use potassium supplements or salt substitutes while you are taking Diovan.
Sadly, I doubt your doc will want to let you stop taking your meds to alleviate the current side effects. Diovan is only effective once it has built up to a certain level in your body and then that level is maintained. Hopefully, the side effects will resolve themselves quickly and you'll feel great!
And, you're right -- it sucks getting old! (And I started dealing with this when I was 44.)
Wishing you the best....
"If we know where we want to go, then even a stony road is bearable." ~~ Horst Koehler