其实，这两个翻译都能说得过去。具体分析看括号：

We've been looking like crazy for you.（ like crazy 为习语，意思是：拼命地；发疯似地，修饰 looking，作方式状语。实际上，look for 或 look at 等并非铁板一块，中间可以加副词修饰语。又如：I was looking anxiously for you. The children are looking carefully at the picture.）

We're going crazy looking for you.（looking for you 为现在分词短语，作时间状语或方面状语，均可）