is it going up stairs? walking a bit of a distance at your normal pace?
At this week--ish, this is when your blood volume doubles or something crazy like that. So your heart is pumping more blood.
My walking pace is usually really speedy but during pg, I was a sloth. I am not kidding. Where previously it would take me 10, the same took me 20min. It blew my mind.
So it might not be the crinone. Do mention it to your dr to be really sure.