Bullshit, bullshit, bullshit.
Drinking winny is just for pussies who don't like needles. Drinking it is certainly more harmful to the liver because of first pass of the 17AA. You don't get first pass from injecting. Also when you drink it, you lose some of it's strength from the digestion process.
Why is everybody jumping on this drink winny bandwaggon. Just inject it.
The pimple as previously said could be a small infection or an adverse reaction to the crystal like suspension that hangs around at the site. It is designed like that as this has a depot effect, which incidentally you do not get from taking it orally either. This can also cause more pain at the site and a little localised temporary swelling. Many people also use slin pins for winny with it being less thick than oily inj. This can mean you don't go deep enough, which could also cause a similar reaction to what you described. Always use orange 1"+ pins to ensure it goes deep enough.