The perfect design was without sickness. Adam and Eve would have lived forever if they had not sinned. They sinned, and death came into the world, along with sickness.
Did it ever occur to you, that God ordained doctor's to be able to cure people?
You know, sometimes the answer is so simple.
Yes, you can pray to God to fill your stomache with food, or you can eat the meal He has put right infront of you.
The things we seek God about are redemption from sin, and the salvation He offers us. We pray for guidance, for revelation, for truth.
As for doctor's healing abilities, yes indeed they are blessings from God, and are to be acknowledged as such. As Jesus said, we have no power on Earth other than what is given from above.