Contact your ISP and tell them that your connection is not working properly. If the speed checker is saying that your having problems with the latency then that may mean you have a fault on the actual broadband connection.
You should also download Malware bytes and give your PC a scan for malware, that may be causing your problems.
And just one more thing which may give you an idea of what's wrong. Re start your PC and when it boot's up again keep pressing the F8 button, this will take you into safe mode. Choose safe mode with networking then see what speeds your getting. If they go back to normal then it's being caused by something installed on your PC.
PS. Did you check to see if port 80 was open in your firewall?