This sounds really minging but i'm worried...

Sorry if this sounds a bit gross but i need advice! Last week i was shaving my underarms but i accidentally shaved over a small skin tag near the top of my armpit. It snagged a bit and started bleeding but i cleaned it up and put a plaster on it. Today (after a week) i took the plaster off and its almost healed but the area is a bit red and inflamed and it feels really uncomfortable whenever it rubs against my skin when i move. Its so itchy too. I'm not sure what to do - shall i go to the doctor and get antibiotics in case of infection? Or should i just leave it to heal on its own. I cant even shave my arms coz i'm scared of making it worse. Help!