What is this on my skin?

im 13 and i got a dog bite on my cheek and its been a couple of days so i felt it and i feel this little ball under my skin where one of the cuts were. i know its cleen becuz i washed it out when i got bit and every morning i spray it with that first aid numby stuff and put neosporin on it. so what is this? and what is a cyst? thats what my mom says it is.