Why is it when you think that all your big problems have disappeared, they suddenly reappear worse than before?

For me, being in the center of generations, problems come and go. My 87 year old mom will be well for awhile, and then kaboom, she is back in the hosptal and because we love her, it is extremely stressfuly. At 67 I have some pretty serious health problem (some are litsted on my home page under my avatar) Just when she starts getting well something else happens, like with the economy like it is, my grandaughter and her hubby lost their home. I love them so much and it seems like my worry gets out of control because I went good thingss for those I love. I feel like when things start going good, then something else happens...at our age and with extended family it is very hard for everything to be good all the time, no matter how much we want it. I just try my best to stay positive about it all, but sometimes it isn't easy.