I need help with dog!?

I found a lump on my dog and I have no idea what his. At first we thought it was a tick in it and when it seemed more close and seemed like some sort of blister or wart. My boyfriend thinks it's a spider bite. I tried to take a picture of her but could not get close enough to show how it was red. When you look at the top seems almost hollow inside. You can see a little blood and pus. Photo: http://tinypic.com/view.php?pic=t69zd5&s=3 Does anyone have any idea what could it be? I am worried that could be serious I just remembered a couple of days I got a tic around the same area and not There was a pink lump on the head of ICT's entered the skin. I wonder if this might have nothing to do with this?

DO NOT WORRY! … it is only a hot spot (which vanishes) Two approaches are necessary to treat the hot spots: the treatment of pain and eliminate the underlying cause to prevent recurrences. Veterinary dermatologist Lowell Ackerman recommends the following treatment in his book Problems of skin and coat in dogs: trim the hair around the wound to prevent further spread of the infection and expose the edges of the injury, wash the area in a soft water-based astringent or antiseptic, be prepared to use antibiotics or cortisone, if washing does not work. Ackerman recommends against the use of ointments or creams because they can seal in the infection and hinder recovery. In severe cases, a veterinarian may suggest the use of an Elizabethan collar to prevent mutilation and give the place a chance to heal.