Dessa got a knot on her a few days ago and today it started bleeding. I don't know if she scratched or bit it or what. I pulled on her hair a little and it opened up. At first I thought this was a botfly but it doesn't look like now.
It looks like it could be a cyst that burst. But no matter what it is you need to take it to the vet so the vet can clean it out and get the dog on antibiotics. And the vet will be able to take a biopsy to tell exactly what it is.
Yes she needs to get to the vet that could easily get infected Nikkia's dad got one a few weeks ago and it looked exactly like that luckily it came back negative for cancer. He is almost 8 and Nikkia's litter was his last we were afraid that since he was older it would be but it wasn't defiantly get her to the vet to get that checked out!
This looks like an infected hair follicle. Apply some warm compresses a couple times/day for several minutes and try if you can carefully squeeze it that the pus comes out (if none comes out, leave it alone and only apply the compresses).
I have done this a couple wks ago in another GSD (not mine) with an hair follicle that looked like your pic and it was gone in 3 days.