X3000 WiFi Light Flashes Rapidly & Abnormally Slow Internet

Hi

In the recent weeks, my X3000 Lunksys Router's WiFi Light started to flash extremely fast. Like the heartbeats of a bird. More than 5/sec & since this happened, the internet has slowed down siginficantly. I usually get 200-600 Kb/s. Now Google's mainpage takes more than 60sec to load!

My network consist of X3000 + a Belkin Range Extender. Both networks are slow.

Why is this?

I tried to change the password & it worked momentarily for a few mintues then it went back.
I restarted everything. The X3000, Range extneder & my devices & no good came.

This problem is like 60% of the time.

For the rest of the time I get the usual speed. However, the problem seems to be worsening.

Any ideas?