That booboo is SERIOUS, you can get phlebitis which is an infection of the blood vessels, you don't want that - you'll see red tracks going up your arm, leg, whatever, leading from the infected area and it's just bad news.

You need to get looked at, and the walk-in clinic is a good idea, you can negotiate with the bill, they often DO give a discount if you're paying cash and a credit card is just as good as cash.

You're talking about losing your foot or getting VERY sick or losing your life maybe, so this is not something to fool with.