I'm having treatment for my back problem.

我正接受背部疾患的治疗。

《牛津词典》

He's working and having treatment.

他正在接受相关的治疗。

youdao

I'm having treatment for my lumbago.

我腰痛正在治疗中。

youdao

But there can be risks involved with having treatment in countries where regulations are less stringent.

BBC: News

Brazilian president Dilma Rousseff, 64, is fully recovered after having treatment for lymphoma in 2009.

BBC: US rejects Hugo Chavez remarks on Latin America cancer

Her predecessor, Lula da Silva, 66, is currently having treatment for throat cancer.

BBC: US rejects Hugo Chavez remarks on Latin America cancer