Fast heart beat changing positions/going up stairs

Wow! 38 is really low. 194 is really high. I would suspect that the 194 may not be the heart rate. How are you determining the heart rate. The rate is usually calculated over a period of time(beats per minute, etc) not just a few seconds. There are different algorithms used which can vary the heart rate.

My heart rate will increase with activity. It can go from resting at 60 to something in the 90's with activity. 
 

pay attention to the changes, see if they cause shortness of breath, pain, dizziness etc. If those happen then I'd call my cardiologist, who should be available. Otherwise, I'd be prone to do nothing, but I'm not a medical provider.

My spouse recently experienced a similar problem. Her resting rate is in the 70;s but it did spike over 100 when doing stairs or other minor activity. She doesn't have AFIB but has COPD. In fact a few weeks back it was shooting up into the higher hundreds until the cardiologist put her on Diltiazem. It no longer goes to the higher levels.

Diltiazem (with Sotalol) also brought down my high rate, but since my normally low rate went too low on the meds, I got a pacemaker (seven years ago) as well. For me, the PM worked very well with the meds - no further issues with slow pulse.