Do I have a melanoma?

Hello everyone, I’m a 21 (m) 5’7 166 lbs

I had went to the doctor last Friday but completely forgot to ask him about something very odd that happened to me about a month ago. The problem is I have this strange brown spot that appeared on my bicep and it hasn’t gone away in at least a month. It itches if I touch it, but I don’t really know if it’s grown much at all and I’m extremely worried. Obviously I know I should go to the doctor but I just wanted to see if it’s just like a bruise or something to be genuinely concerned with.