Sudden internet speed decrease for no apparent reason

It all started when I noticed it yesterday after I re-arrangesd my room. I cleaned up some cables and moved my set up around to spice things up a bit. I did indeed move my router and mode, but I hooked them up exactly the same way as before, wires are basically just laying in different directions. I'm using the same outlets, cables, and everything. For some odd reason, my internet is pretty slow now. Even small applications such as Skype as trouble sending simple IM's out sometimes. I live in New York and my ISP is Time Warner Cable. We pay for 15mbs download and 1mbs upload. Usually when I do a speed test we get about 16ish download and 1-2 upload depending on the day and traffic and what not. I have a cat6 ethernet cable going from the modem to the router, and a cat6 cable going from the router to my desktop PC. Everything else on the network is wireless. (My Mom's PC, my iPhone, and our smartTV). So we don't really have a ton of traffic in our house. Every device is being slower than usual. There is also a password on our network. When I first set up my router and modem I had it in a little shelf on my desk. It was very enclosed and tight and there were cables everywhere so I thought maybe I had some type of interference or cross-talk I think is the official term for it, so I moved them both out in the open for better air flow and to seclude them from other devices and wires. I tried to seclude the ethernet wires as well from other wires to prevent cross talk as much as possible. I made sure plugs were secure multiple times on everything, I restarted them both a million and one times, I did multiple virus scans, and nothing seems to work. I'm a gamer and a student so I really need an decent internet connection so I'm kind of worried. (I have some online classes). Time Warner is infamous for throttling their customers internet so maybe that could be the problem? When I do the speed test now I only get like 4-5mbs download and 0.10mps upload. Ping averages at 20-30. Here is my speed test result I just did: http://puu.sh/6Hu4b.jpg

Not sure if there is much I can do about their internet throttling but let me know if there is!
I have a Motorloa SURFboard Model:SB6121 modem (Cable Modem) and a D-Link DIR-615 Router. Both are fairly new. Although, I have been having some odd problems with the modem, atleast I think it's the modem. It will randomly disconnect from the interent and the 2 blue upload and download lights on them will turn green, or all lights will turn off besides the power indication light. Not sure what to make of that but to fix the problem I have to unplug the modem and plug it back in. Sometimes it will fix itself, though. The router seems to be working on par.
I opened the command promp and typed in ping google.com and got an average of 42ms.
Windows can't find any problem with the network either. I'm only noticing slower speeds. My mother said she hasen't downgraded our interent speed plan at all and we're paying for 15 down and 1 up. I realize that it won't be EXACTLY as advertised but we used to get very close and most of the time a tiny bit faster than what they advertise. I watch a ton of youtube videos and game and skype, I watch twitch streams once in a great while. So maybe it's Time Warner being dumb. I can't wait till Google fiber is available in my area.

I can't think of any other significant details to share with you guys so I'll leave it at that. Thanks for your time and effort and any help is greatly appreciated. Sorry for such a long post. Let me know if there are anymore details that could be of assitance. Thanks!