Difficult Breathing And Talking When Tired. Why This Is Happening ?

Hello, I had a bit more difficult period and I feel tired, sometimes even if I just woke up in the morning I do not quite feel myself especially when doing some effort, I feel dizzy from time to time, and what worries me is that when I go to sleep, if I am somewhat more tired, I cannot realx in the bed, I feel like I can t breathe well and I have hot waves and tremor (that appear instantly and my heart starts beating fast like I feel I can lose my conscience or have a heart attack or something). When it happens, I also feel like I don t want to talk, I find difficult to talk much. And my vision also is a bit blured. Can it be only the fatigue? What should I check? Sorry for my english Thank you