Antibiotics are not a remedy to decrease lymph nodes. The lymph node traps infection and thereby enlarges. Also, if you keep touching the lymph node then you are not allowing it to decrease in size. You must leave it alone for 3-6 weeks and then touch it gently to see if it has decresed in size. If it has then leave it alone again and check it in another 3-6 weeks.
They would have put you on the antibiotics to see if it helped diminish the size for ONE reason. And that is that your dr suspected there was an infection somewhere in your body that your immune system was reacting too, thus causiing enlarged lymph nodes.
The steroids are anti inflammtory and used for inflammations, my instinct would tell me that your doctor suspected some sort of pelvic inflamation so he tried steroids to see if that would help.
Thirdly, labs should be done as well rather than jumping straight to a biopsy. Have you had any labs done?