Staphylococcus aureus

Recently i have been diagnosed with Staphylococcus aureus i had a bicycle accident like 2-3 months ago. I cleaned up the bruise with 70% alcohol and put a plaster on it. Almost 2 weeks later i start getting a itching sensation in my knee around the area where i had the bruise. After i started to see little pimples there around the area after a few days i was trying to get the puss out of the pimples and i noticed like a few hours later my knee started to swell. I went to the doctor like 3-4 days later. He gave me Amoxicillin clavulanic acid and he placed a band around my knee and told me to keep the gauze underneath of it damp. And to get some rest. I did not really found that that helped because by Monday one of the pimples on my knee was opened and a large piece of puss came out. I went to the First Response they made an incision  in my knee to get the puss out. And i had to use a syringe to squirt water into the incision to get out the puss. That worked and the swelling went down. 1 week later the swelling returned. I went to the doctor again and he did a swab of the blood that came out form where one of the pimples were and sent it to the lab to be tested for bacteria's. A few days later the pain got extreme i went to the First Response again the doctor there gave me pain killers and he told me that it was a skin infection and he said i would have to wait on the results from the swab in order to know what treatment i have to follow. A week later i found out that i was diagnosed Staphylococcus aureus. I went to the doctor today because after taking pain killers for a few day the swelling went down. Then 2 weeks later thats today the swelling came back i went to the doctor and he advised me to visit a Dermatologist. And he gave me a prescription for the same antibiotics i was using so at this time i'm now on my 3rd box of Amoxicillin clavulanic acid. I would really like to know if any of you Dermatologist can give me any advice or have you seen or heard of this situation before. I'm frustrated i'm 17 living in dorms with 7 other students we are all sharing the bathroom and kitchen i don't know if this information is relevant maybe i got the infection in this building. I'm asking you for your advise.