Dear mdaniels,
I have more than 31 years of post-donation experience. I have encountered several types of physical problems, from problems relating to silly reasons to a serious problem due to an elevated value of serum creatinine. Yet I came back every time.
I had similar problems like you. Since your reports are normal, you need not worry about your health. Like me, it can be due to your mental anxiety regarding the health of your existing kidney. My advice for you is to
(i) sleep at least for 8 hours daily
(ii) try to maintain a BP close to 110/70
(iii) meditate for an hour, if possible
Nothing to worry. Have no fear.
Best regards,
BB