Old Beer Cans

Can you get sick from drinking old beer?
Basically, I bought a barrel last weekend, but probably ended only slightly more than half of it. Therefore, it has been a week and is likely to be colder than about 65 degrees there. Now, I know barrel Beer is not pastuerized, and may "spoil." But if cold again tonight, and get it cool, I become sick if I have to drink? And you begin to shape inside the barrel?
There is a barrel last approximately three weeks before going flat. Even after drinking remains … simply not good work.
Beer Cans