I think that the ruptured disk is the most likely explanation for your pain. I think the boil on your leg is just a separate problem and probably not related to the major problem with the pain.
The irritation of the affected nerve roots in the back is probably the reason for your sensation of pressure in the pelvis.
I would recommend that you take a relatively high dose of an anti-inflammatory for your back unless you have a contra-indication for this such as problems with a stomacjh ulcer..Aleve 2 tablets twice a day with food would be a decent option...
You will probably benefit from an oral antibiotic as well as topical treatment for the boil...
I hope this information helps. Further questions are welcome if you have others. If my answer has been helpful and to your satisfaction then please remember to press the "ACCEPT" button. Thank you and Best regards,
Anthony Bray MD