Backfire of CFS!

Being optimistic for over 3 months, I have been suffering from a serious backfire of CFS for over a month. Heart palpitation, shortness of breath are my primary symptoms. I had to constantly cancel my working schedule in order to get rest. Terrible!

I have been thinking what triggered this backfire and why it took so long to recover (I am still not recovered yet). Lacking oxygen is what I suffer the most when I had shortness of breath: I do not have strength to inhale air. I realized that this symptom happens after I overuse my energy. Back to April I had significant improvement after I changed my diet but why now, having being in better situation in every aspects (mental, financial), I still have such an attack from this monstrous disease?
I blaimed soy products, iodine overdoes, but today my "final" complain went to TALKING! Since I got better after I changed my diet, I increased working hours (I work as a teacher) and I realized that might be a problem! Because every time after 2 or 3 classes I literaly felt exhausted (More miserably I would started to suffer from shortness of breath for couple of days, sometime even longer). Talking is especially hard for me because when we (human) talk, we only breath out. We can only breath in during those intervals of sentences or words. So talking requires certain amount of stored oxygen inside our bodies to use. And my body is so weak sometime that I could not accomplish such a regular task which a normal person can do it without conscious intention.
I have already thrown away the inhalers that doctors gave me long time ago. They didn't help. I believe the only thing that can help me is talking less, doing more cadio exercise. Of course, it takes time. A lot of time. But I have no choice.