I know a guy who started getting itchy skin break-outs after smoking weed. This only started happening to him when he got older, so he had to quit.

As far as the brownies, it's possible that there is an ingredient that you're allergic to. You can't get an actual "cold" from weed, or anything other than the germ itself.

Because I have Celiac, and other food intolerances, I eat non-marijuana special-diet brownies that are gluten, dairy and soy free. Got about six boxes of them in the freezer.