There are 17 times in the Gospels when Jesus healed all of the sick that were present. There are 47 other times when He healed one or two people at a time.
Nowhere do we find Jesus refusing to heal anyone. Jesus said that He could do nothing of Himself, but only what He saw the Father do. His actions are proof enough that it is always God's will to heal!
Jesus provided for physical healing as well as forgiveness of sins. The very word "save" (Greekk.-"sozo") is translated "made whole" in reference to physical healing in Matthew 9:22, Mark 5:34, and Luke 8:48. James 5:15 says "the prayer of faith shall save (Greek.-"sozo") the sick." Many scriptures mention the healing of our bodies in conjunction with the forgiveness of our sins.
Healing is a part of our salvation, just as much as the forgiveness of our sins.
It is God's will that no one should perish, but many do because of their unbelief. It is God's will that we all be healed, but not all are healed because of failure to believe. It is a mistake to assume that whatever God wills will automatically come to pass. We play a part in receiving from God by believing His Word.