Thal Minor or Hypoglycemia?

[SandsofTime]

Hello everyone
I have known my Thal minor since I was 16 and got diagnosed after having bouts of fatigue. Lately, I checked my Hemoglobin and its pretty good - 14.5 in a reference range of 13.2-16.2. Luckily, I have delta beta trait which switches on production of HBf and improves the overall levels. I have Hbf level of 20%, with much of the rest occupied by HBA1. But I still can't shake off feeling fatigued easily. First I thought it was lack of exercise, so went to gym and swimming for sometime. Exercise made things worse, even if done for only thirty minutes. I become completely drained, disoriented, nauseated, and trembling. Tried taking sports drink only to find it making nausea worse. Only a nap for an hour or so would do the trick to get back to normal. For sometime, I resorted to drinking protein shakes for weight training, which made things much better after about 20 mins of intake.

Any ideas why a protein shake helps rather than a sports drink with glucose? Does this provide any leads I should investigate? Somehow I don't think its the thal trait since my HB levels are good. I have a normal diet and avoid sugary stuff, coffee etc. Despite being skinny, I eat more than my share compared with others of larger body mass.

Thanks
SandsofTime