。
She's always nitpicking at me.
Literal
She [topic-は] my fault-finding [only-ばかり] does.
あら探し ('fault-finding, nitpicking') is built from あら (rough spot, flaw, defect) + 探し (searching) — 'searching for flaws.' The same あら appears in 粗 ('rough, coarse') and 粗探し is the kanji form, though あら探し and 粗探し are equally common in writing. ~ばかりする ('does nothing but X') is a focus pattern with a faintly exasperated edge — implying habitual, one-sided behavior. The whole sentence is a complaint against someone's chronic critical attitude: she's not just occasionally critical, she does it all the time.