Extreme Exhaustion??

So I woke up this morning feeling not good, but not really sure what it was (thought it might be allergies) We went to our appointment, and everything was just fine-heart rate was at 155!- and then I went about my day. Well throughout the day I just kept feeling more and more tired, but I only had one more client left. By then I felt almost nauseated and knew something was not good at all! I stopped on the way home to go number 2, bc that needed to happen, and then went straight to bed when I got home. Just woke up after sleeping for 4 hours, thinking “what was that????!!!” Just extreme exhaustion? Any ideas/comments appreciated!!