Suggest Treatment For Boil Inside Ear

I took my 15yr old daughter to the hospital 4 days ago because she had what looks like a boil right on the inside of her ear so they gave her bactrim then last night I took her back because it wasnt getting smaller so they drained it and got some stuff out of it and gave her another anti biotic calleddioxycycline hyclate they told me to give her both of them it doesnt look like its any redder or any bigger today but how will I know if the medicine is working or not do you think they will have to drain it again