What should be capitalized?

she had a test sometime in november at a walk-in clinic and it was negative.
Answer:
She had a test sometime in November at a walk-in clinic and it was negative.

Correct.

(I do wonder about the person who wrote the original sentence, though. No comma for the compound sentence? Vague use of "it"?)

=)

In this sentence, the word "November" should be capitalized. According to English grammar rules, months of the year and days of the week should always be capitalized.