I saw something strange in my room at 4 AM - what should I do?

Assalamu alaikum. I'm 15 and until recently I didn't have much guidance and was distant from Allah. Lately I've been trying to get closer to Allah and reading the Qur'an, and since then some odd things have happened. The first time was around 2 AM when I was reading a Seerah book for the first time. I heard someone sneezing very loudly downstairs, but everyone at home was asleep. It kept going for at least three minutes straight, so I knew it wasn't a normal person. When the sneezing stopped I heard footsteps coming up the stairs toward my room, and the sound faded as soon as they got to my door. I was really scared, so I opened the Qur'an and slept. The second time happened in a dream: I saw my brother with a beard on a train staring at me in a very evil way (my brother is 17 and doesn't have a beard). After I woke from that bad dream, I saw that same figure sitting on the edge of my bed in the dark staring at me. I called out thinking it was my brother, and it answered, but the voice was much deeper and not like him. I immediately said a'udhu billahi min ash-shaytan ir-rajim and it vanished. What can I do to protect myself before sleeping? And does anyone know why this might be happening? If it helps, I'm trying to stick to reading Qur'an more and praying on time, but I'm still learning what else to do. Any simple practical tips or dua you use before bed would be appreciated.