歯がすごく痛むのです。

tooth

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

terrible; dreadful; amazing (e.g. of strength); great (e.g. of skills); wonderful; terrific; to a great extent; vast (in numbers)

to hurt; to feel a pain; to be injured; to be spoiled (e.g. food)

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

be; is