Hi I was walking across a tree today when I felt a faint bump on my arm. I turned around right away to my left and saw no one and then to my right was a guy holding a trolley coming towards. I was changing 30 minutes later and checked the area yet finding no visible puncture wounds except for my shoulder acne and no blood. However on my hoodie there was a wet spot slightly above the area? The small wet patch wasn't red in color. Is it possible that someone poked me with a needle? I've been hearing a lot from other people. Can HIV be transmitted in this manner?