Garry's Mod ping problems...

Ok… So every time i load up Garry’s Mod my ping just skyrockets from about 20 to 300-700.
Its NOT my internet connection, I’m not downloading/streaming anything at all.
All other games on my computer run perfectly in multiplayer… I’ve tried looking this up so many times and I’m the only one with this problem it seems.
And before someone says its my internet connection which i know it really seems like it is it most certainly isn’t.
Any ideas?