I bought a pulse-ox online which slips on the end of your finger and displays both your oxygen level and HR. If you are having an episode you will know how high your heart rate is going and if it's a-fib you will see it jumping around all over the place. It was well worth the $75-100 I paid for it.
I have over 600 miles jogging and walking with them on. Chest strap and watch. Currently wear a bowflex (avail any sporting goods) and they DO pick up my palps (pvc's). You will see a jump in the heart rate a couple seconds after you feel it.
Check Polar heart monitors. You wear a lightweight elastic belt around your chest, just under the breast and it sends data to a wristwatch-like device. The better ones have high and low setpoint alarms that will alert you when they're exceeded. I've worn them in the past, and you forget they're even in place.
I use a low cost (e.g., Walmart) stethoscope to listen to my heart beat... and count that against a full minute count. I can also here the irregularities I suffer from due to atrial fibrillation.
There are also heat monitors that athletes wear to keep track of their HR while exercising. I sometimes use one of those if I want to look several times a day. This will not give any indication of irregularity other than a variation in the count it uses to compute. I think it measures for about 10 seconds and multiples by 6 to display the BPM.