Swimmer's ear is usually meant to refer to an infection in the outer ear i.e. the part of the ear canal that is in front of the ear drum. So-called inner ear infections are those which occur behind the ear drum. Outer ear infections can be very painful and do often present when patients notice that pressure on their ear (for example when sleeping with that side of the head down) or pressure on the ear lobe is very painful. Swimming is a known risk factor for outer ear infections as exposure to water and any bacteria in the water can lead to painful infection or irritation of the ear canal.
Given your new onset of symptoms the best thing for you to do is to see your regular doctor
right away for a more thorough exam. You may well have an outer ear infection
(i.e. swimmer's ear), but it is also possible that you have an inner ear infection, a problem with your ear drum, or even a foreign body inside the ear canal. Your physician can use an otoscope to take a look inside your ear and evaluate both the ear drum and outer ear canal and determine whether you need additional treatment such as an antibiotic for an ear infection or whether further evaluation with an ear specialist
is warranted. In the meantime, you may want to stay out of the pool!