Lump/sore near penis

Hi there! Before I get into this, I DO have a vet appointment scheduled. But, they can’t get him in for quite a few days. I have had him wearing a cone to prevent him from licking. This started probably about a week ago. Well, the licking obsessively anyway. I guess the lump/sore could have been there longer. I just didn’t know to look until I noticed his licking. The lump you see is near the opening of the penis. But it is not the actual opening. The red raw patch at the base of the penis didn’t start until after I noticed him licking, so I’m thinking that’s just irritation from the licking. There is not a lump down there. The lump/sore near the tip has been getting progressively larger. As it’s getting larger, the skin around it is becoming darker, almost a blackish hue. There is a little bit of discharge occasionally on the sore near the tip of tip. His breed is boxer and mastiff mix if that matters. He also has had pancreatitis a few years ago and also has a history of heartworms (also several years ago). I know the vet will give an answer at the end of the week, but I just need some clarity before then. My deep dives on Dr. Google aren’t helping ease my mind. Thank you so much!