little bumps on my torso?

so i've always had a bit of acne on my boobs, but recently when i spent the night at a friends it just spread like wildfire. it wasnt so noticeable at first, i thought it was just the acne acting up. but tonight i toke a shower and there were a bunch of these little bumps on my breasts, torso, hips, back, shoulders neck, and it's beginning to spread on my upper arm. they look like whitheads but then some look like pink bumps, the sizes of them range from a pinprick to a pencil eraser. but they dont have liquid in them, my mom thinks they are allergies but im not allergic to anything. another thing is a week before this i got this circular thing on my knee it was the size of a dime maybe a nickle, it got raised a bit and started drying out around the edges, its almost healed but you can still see it.

please help me!!

Pheobe