Healing......what do I believe??

Does God will for everyone to be healed and the reason we are not is our lack of faith?.....or is it that we live in a fallen world and so disease and sickness are just a part of life and God will use all situations to bring us closer to him?

In light of our family situation, dealing with Chris' stomach I feel torn between the two. I WANT to believe that God wants to heal all disease....but then where does that leave us? Does that mean we don't have enough faith??....or is it that God is using Chris' struggle to refine and mold us into the children he has called us to be?? I suppose in this moment I am just relying on daily strength from God to help our family.

Does this mean God wants Chris to be sick- no, I don't believe that.
Does this mean I will stop praying for Chris' healing- no, I can't stop asking....

I'm not sure where to go from here except to draw closer to God through all this. I mean I've seen people healed before my very eyes. I know that it is possible and so I struggle with the fact that Chris remains sick. This is one part of Christianity that I wish I could figure out and have all the answers.....