It seems like if you never had these problems before, you must have gone over your bandwidth with your current Internet Service Provider (ISP). If you have had reoccurring problems with your ping, your best bet is to upgrade to a faster and more efficient service, or just upgrade your speed and bandwidth with your current ISP.
You'll want to check whats cutting your internet down. Whether its exclusively just online gaming, downloading etc. If you have an 802.11 b/g/n wireless router, and live in an area that is largely populated or something like a suburb, someone may be leaching off your router if it isn't heavily encrypted with a password (if its WEP, it is easy to crack. A little kid could crack it. Change it to WPA2 or something).
If none of those are your problems, then call your ISP about it and see whats going on. It might be your ISP's network being interfered by something.
If you are STILL having problems, my only guesses is you are playing WAY too much online games, so you've gone over your bandwidth limit and your internet is slowing down. Usually on most services offered by ISP's have a limit, so if you pass say 10GB's on your ADSL2+ internet it will slow down to a speed in range of ADSL+ or ADSL. If you just have ADSL, and you go past your limit it will most likely go to a dial-up connection which is REALLY REALLY slow (like download 5KB/s slow). If you are using wireless modem like a USB modem from a mobile company, you shouldn't play games with there atrocious internet speeds.
If you don't want to spend more money, just cut down on your internet usage, like spending less time on games or giving up certain games altogether. Reply back if these aren't your problems.