Hi, i would send him to the ER !!! they can do all the testings, it's worth it!!! Even if it's nothing, you will feel better, good luck!!!
It could also be Afib with a rapid ventricular response -- my particular problem. Either way, I agree with tom, get to the ER, better safe than sorry. Keeping you both in my thoughts and prayers.
This could be SVT or Supraventricular tachycardia. It's hard to say with the symptoms you've provided. It's best to take him to the ER, and hopefully you've done this already. Molease get back to us with what is going on. Good luck!