Internet going very slow out of nowhere?

In my room I use my laptop with wireless connection from my mom's router in the living room, the next room over from mine. Since two days ago my internet has been going very slow, but my laptop still runs normally. If I try to watch videos on youtube it keeps stopping to buffer and doesn't load fluently, same with the thumbnails on each page, all load slowly. The connection signal seems to be normal and even says "excellent' when looking at it's status. I also noticed if I try using my iphone with the Wi-Fi connection it will run slow, but faster when I turn Wi-Fi off.

My laptop is regularly checked for viruses and scans etc, I cleaned out cookies just to see and updated flash, still same problem. If it matters I'm using a Hp pavilion dv6 with comcast internet.

Try to restart the modem first, some routers require a restarts frequently and check anything running behind the wall on your computer like apps, Torrents, etc. Which is consumptions a heavy bandwidth try to close them. Even though signal is excellent. Not that mean internet would be fast. Try to disable and enable the Network card in your PC.

And check whether Router has a Key, otherwise some neighbour may using it.

A system eng 6 Years

Someone is using up bandwidth then, plus the further away from the modem/router the connection gets worse. Try contacting your internet service provider.