if it's not one thing, it's another!

"If it's not one thing, it's another!" Something that you say when many different things are going wrong in a short period of time. This is to say that if "one thing" is not causing a problem, "another" is or that you are busy with too many things to do. — ни одно, так другое; то понос, то золотуха; вечно что-нибудь да случится; вечно что-нибудь да не так...

Example 1: "First the car broke down, and now I can't find my keys! If it's not one thing, it's another!" — Сначала машина сломалась, сейчас вот ключи не найти — ни одно, так другое.

Example 2: "I've got to wash the dishes and do the laundry, and now I hear the baby crying! If it's not one thing, it's another!"

When it seems that no matter where you look there is one more thing you need to do or you discover another problem, you might say "If it's not one thing, it's another!"(GoEnglish.com)

сf.:
[беда не приходит одна]
[that's the story of my life]
(that’s / it’s) always the 'way
Typical!
[that's the way the cookie crumbles]

It's just one thing on top of another. — Все одно к одному.