Baby suddenly waking at night for 2 to 3 hours, help!

Has anyone ever experienced this? My daughter is 7 months this week and has sleep 12 hours a night since 4 months and has slept through the night since before that. This past week she has begun waking around midnight to 1 and will not go back to sleep for up to 3 hours! She is crawling, standing, side stepping while holding on and is very active. She is also teething. Typically she takes a morning nap and an afternoon nap. Any recommendations on how to handle this sleep regression?! Thank you!