Suggest Remedies For Blood Filled Pimple On The Knee

I have a pimple like bump on my leg (right side inner knee) it is perfectly round dome shape with dry blood at its peek ( when its not bleeding), and will not heal. I went out to dinner and it began to bleed and I could not stop it by applying pressure with tissue, it produced quite a bit of blood soaking through my jeans. I finally had to ask the restaurant staff for a band aid. The bleeding finally stopped, now it looks like a volcano readying for an eruption once again. I’ve done my own homework by looking at photos and it doesn’t seem to have the same characteristic as a cancer bump plus it’s on the inside of my leg and I usually ware long pants. Any help you could give me would be appreciated!! Thank you.