Pro Mass is my weapon of choice too mate when it comes to a gainer
Get the strawberry and banana flavour and mix it with a scoop of rasberry or strawberry whey (if you need the extra protein), throw in some ice, 500ml of water and blend...
Trust me - You'll love it!
With regards to spots, it does sound wierd from protein mate, you sure it was the protein?
Where are the spots? Face, back, neck?
Are they white (i.e full of puss) or just red pimples?