My 16 year old son has a puss filled bump on his knee. He asked me to look at a bug bite on his knee, and before I looked up any information online, I popped it (there was much more pus than I would have expected), cleaned to with alcohol, and covered it with neosporin and a bandaid. It is red, sore, swollen, and he first noticed it 3 days ago. He has thick curly hair and occasionally gets ingrown hairs. Once I googled puss filled bump on knee , I started to worry about MRSA. He does not have a fever. Should I take him to a doctor, or at what point should we see a doctor? Thanks.