Yes it looks like a big pimple but it usually is a boil. A boil can actually be dangerous to pop-the pus instead of coming out spread into the surrounding tissue and the other tissues become infection which is called cellulitis. A doctor usually removes the inside since it is like cyst material and not just a runny pus. Do not touch it either if you get the pus on you wash your hands immediately since it may contain staph or another bacteria. Either way don't try to pick it. Have your Dr determine the difference, treatment, and why you might have gotten the boil.
Yes it is probably a boil. Boils are very painful. I don't know your situation but a lot of people in this country can't run to the doctor because their jobs don't offer insurance and it is way too expensive to buy (well, that's another story). Anyway, if you can't, or don't want to go to the doctor you can choose to try to squeeze this boil out or let it run it's course. A boil is very painful and squeezing it (or popping it) would relieve the pressure. If you don't choose to squeeze it, it will eventually begin to drain. Either way, once it has been opened up it is very important to keep it covered with bandaging and to keep an antibiotic ointment, such as Neosporin, on it. Change the bandage and apply the ointment several times a day. The doctor, if you can go, will have a quicker fix. He will lance it (cut it open) and give you a prescription for antibiotics and probably tell you to keep Neosporin on it.
Note: Squeezing it is not that easy since a boil is deep under the skin and it will be painful but will also be a big relief.
Note: Squeezing it is not that easy since a boil is deep under the skin and it will be painful but will also be a big relief.