Had my belly pierced for four weeks, can I change it?

you are clearly more pron to infection then your friends, do not change it. Wait until its not infected and stop putting peroxide on it you need to wash it 2 to 3 times a day with antibacterial soap like dial or softsoap if you change it now it could get more infected and have to take it out let it close up and then get it re pierced and you could get a keloid on it do the research on that