Is ''feeling like a nutcase'' considered a simile?

Yes, it is a simile.

Explanation:

A simile means to compare one thing to another. When saying "feeling like a nutcase" you are comparing yourself to a nutcase. Therefore, this is a simile.

the difference between an explicit and implicit meaning is that the explicit meaning of a poem is that the detail is exactly defined. nothing is left to interpretation. an implicit meaning is an implied meaning. kabir's poetry is both explicit and implicit in that it can be interpreted on different levels. the explicit meaning leaves nothing to interpretation while the implicit meaning leaves lots open to interpretation. an example of this is found in the poem "rumi and the spiritual lover". 

answer: the sentence in the text that contains both the topic and the author's single most important idea about the topic

explanation: aww pineapple so adorable