Pimple on dogs head?

Hi. Last week what appeared to be a pimple appeared on the top of my dogs head. It seemed to be becoming a whitehead just like a pimple would. Yesterday it popped just like a pimple would with white pus coming out. I put some bacitracin on it and now today it's basically back to the size it was when it first developed. Does anybody have any experience with anything like this?

Sorry but I don't have experience about this before on my dogs! Hope your vet find out about this and give the best treatment for this! Keep us update hope it will be okay soon.

Possibly a sebaceous cyst. Is the pus almost solid, kind of cottage cheese texture? If it is a cyst it needs totally clearing out of pus to heal. If it keeps reoccurring you will need vet prescribed antibiotics.

Hate to say it but that looks like a Tick to me ?????

Another vote for a small sebaceous cyst. If so it should be OK with what you have done. As Seacrow says, make sure you have all the cheesy stuff, (which will be keratin not pus), out or it may recur.