My internet has been really slow in the past 2 weeks.?

Back in like February, I got a mac and its in the basement, the modem is upstairs. But this just started happening like 2 weeks ago. For example, for facebook to fully load it takes like a minute and a half. The "facebook bar" (blue bar on the top) goes on right away and everything else slowly starts coming but its just getting slower and slower and its starting to piss me off. Suggestions?