Answer:
Sounds like you had a skin infection known as a furuncle or boil. You probably are nauseous from the antibiotics. Once they drained the infection it sounds like they packed it with xeroform which helps treat the infection. The antibiotics and following the instructions they gave you should help get rid of any remaining infection. Also if you are a diabetic high sugar levels put you at greater risk of developing these type of infections and make it harder for you to heal.
These cysts are usually caused by hot weather and humidity. So you should keep the area clean and dry.
Now you should take antibiotic and anti-inflammatory. If you are nauseous you should receive the meds through injection. Though the problem often subsides after a few days rest.