Hello I Am A 46 Yearold Woman And Have Congenital

Hello I am a 46 yearold woman and have congenital heart disease. I have had two open heart surgeries. Today I was out snowshoeing and my heart start racing and i couldn't catch my breath. Husband said my complextion was grey. Not nice and rosey like usual. We took a bit of a break than continued on for two and a half hours in the mountains. It took about 4 hours to feel some what better.
Can you please help me with this.
Tammy