It's a question on leprosy: What did Jesus do regarding the Jews believing that some diseases were sometimes due to sin?
I suspect the problem is that your question is just too broad and opinion-based, and more of a discussion-starter (which isn't what this site is about) than a question that calls for a specific, objective answer (which is what this site is about).
See these help articles:
- How we are different than other sites
- What topics can I ask about here?
- How do I ask a good question?
To make your question work here, you would either have to ask for the perspective of a specific denomination, such as Roman Catholics or Lutherans, on the question, or you would need to ask for the Biblical basis for a particular viewpoint on the question.
I would also suggest making the question more specific, with less discussion-like speculation. Think about what, exactly, you want to know, and specify which denominational viewpoint you want on that question. If you do that, your question will fare better here.
I hope this helps.
Your last (somewhat tangential) paragraph in particular isn't a good fit here: questioning why Jesus didn't do some things is off-topic.
The rest of the question is actually a verse search question, which are generally not considered acceptable here (see here). The answer is either "no such verse exists," or perhaps something like the answer I've provided.
I think your question should more be on the lines of:
Can sickness come from sin? What did Jesus say concerning this?
You seem to be asking a question already holding to an answer, that sickness coming from sin was merely Jewish superstition. Personally, I think there can be sin unto sickness, just as there is sin unto death.
1 John 5:16 If anyone sees his brother sinning a sin not unto death, he shall ask and he will give life to him, to those sinning not unto death. There is a sin unto death; I do not say that he should make request concerning that.
Also consider Miriam's rebellion resulting in her leprosy:
Numbers 12:10 And when the cloud had departed from over the tent; there Miriam was, leprous, as white as snow. And Aaron turned toward Miriam, and there she was, leprous. (11) And Aaron said to Moses, Oh, my lord, please do not lay this sin upon us that we have so foolishly committed.