Can a 3.5 month old be teething?

Can’t tell what is teething and what is 4 month sleep regression...

- She used to suck on my finger if she put it in her mouth, now she chews on it.

- She is more irritable over the past two days

- Sleeping has been getting progressively worse over the last two days (waking every two hours at night and struggling to self-soothe, napping less than 45 minutes before waking up expecting to nurse)

- She hasn’t been nursing as well as normal (fussing more)

- She started drooling recently

**no temperature, seems healthy**

If this is teething, what can I do about it?