Why have I been seeing a lot of pop ups online lately?

[bamabuggin13]

I use Google Chrome & Avast internet security. I have a Dell, Windows 7 laptop that is just over a year old. The avast has been working quite well. However, over the past couple of days my internet browsing has been interrupted quite frequently by numerous types of pop up ads!! Anything from Pinterest to my school work has been interrupted. The only page I haven't seen any excessive ads is Facebook. I have run security checks on my computer to check for viruses, but nothing is found. I checked my pop up settings and everything is set to be blocked, yet I still see all of these annoying ads. My screen right now has about 5 different animated ads on it. I'm so frustrated & annoyed!!! Any clue as to why this could be happening?? I really like avast, but if you suggest that I change internet security, what free software could I download online??
Robert: I had no idea there was a such thing as anti-malware!!! I ran a antivirus scan