In the song Chercher by Kotoko there's the line

> 心配性｛しんぱいしょう｝と言｛い｝われても　ハラハラのしどおしよ

And in a subtitled video it gets translated to: "Even if you say I'm a worrier, you're anxious with me"

It all makes sense expect that どおし part...
Is it supposed to be 同士｛どうし} ? But if so, how come it's written with a different spelling that my IME doesn't acknowledge?

I tried researching this and the best I found is this https://detail.chiebukuro.yahoo.co.jp/qa/question_detail/q1216623117 
but I don't know. Does anyone know what this どおし is supposed to be and why it gets spelt this way?