Why?

Why? Why? Why? Why? Why? Why? Why? If my cancer is back, how does it prosper me, not harm me? God says in Jeremiah 29:11, "I have plans to prosper you, not to harm you." Why now? I am teaching full-time. I Thessalonians 5:18 tells us to be thankful for everything. I am not thankful! Some day I will be, not now. Yes, I have still told God thank you. I don't' understand. I didn't understand 3 years ago, and I don't now either. True, I told God last year, that I would rather move up a stage than my sissy be above stage 1. She is only stage 1, and now I might be moving up. I won't know until May if my cancer is back or not. I've been crying and I have been questioning God. I know God has a plan, and I have to trust Him. It is going to be very hard to do. I do not like this at all.