17 is nothing to sneeze at (pardon the pun). Good on you for not turning around right away!

Did you use your inhaler? I have allergy induced asthma, and find if I'm not breathing well while on the bike, even if I'm not struggling, a hit off the inhaler makes a big difference.

And if I don't sound like a freight train at the end of my ride, I always think I slacked off.