When you are an enlightened Buddha do you have no more worries or fears and desires? All Buddhist traditions hold that a Buddha is fully awakened and has completely purified his mind of the three poisons of desire, aversion and ignorance. A Buddha is no longer bound by Samsara, and has ended the suffering which unawakened people experience in life.

The term buddha is also used in Theravada to refer to all who attain Nirvana. Within the Buddhist tradition, this term has commonly been interpreted as the extinction of the "three fires",or "three poisons",passion, (raga), aversion (dvesha) and ignorance.

But does this all mean that fe Siddartha Gautama never worried about his health or was never doubting about hisself whether he was doing good or not?
The term buddha is also used in Theravada to refer to all who attain
  Nirvana.


please let me make a correction, in Theravada a term used to all who attain nibbana is arahant

Buddha is one who only attained nibbana on their own having discovered the path to nibbana for themself without reliance on anyone else


  But does this all mean that fe Siddartha Gautama never worried about
  his health


i think it means that as a Buddha he didn't


  or was never doubting about hisself whether he was doing good or not?


as a Buddha he could do nothing BUT good, because with awakened beings virtue and skill are natural, it's like a compass hand which points at only one directon

Doubt is one of 10 fetters, which is abandoned at as early as the sotapanna stage not to speak of the arahantship