When staphylococcus is NOT MRSA (i.e. it's MSSA) it's best treated with either cloxacillin (by mouth or IV) or cephalexin or cefazolin. Augmentin which is amoxicillin/clavulanate is not the best choice. Other antibiotics CAN be used for Staph infections such as Septra (bactrim in the States), and it's a good drug for staph, though it's generally saved for patients with MRSA. Clindamycin is another good one. Fluoroquinolones have anti-staphylococcal activity but should NEVER be used alone as resistance can develop quickly.
I see you've been doing some reading about Staph. Excellent. Yes staph can enter your bloodstream and from there it can seed your heart valves, bone etc; however, if you're otherwise healthy and you don't have an actual central venous catheter (i.e. an indwelling intravenous line to one of your larger veins), the chances of it going to your blood are much less.
It's possible that after any surgical drainage, you may just need a longer course of antibiotics, or another option is to give you something intravenously. Generally for Staph which is methicillin sensitive (i.e. MSSA) we use cloxacillin or cefazolin IV here in Canada...in the States they often use dicloxacillin, oxacillin, naficillin (instead of clox) and they also have cefazolin. Augmentin can be used to treat Staph, there're just better choices.
I wonder, though, if your doctor gave you augmentin because of the location of the lymph node. Any infection located in the inguinal region has the possibility of being contaminated with stool organisms (even if you're a clean person!
. Anyway, I hope you start to feel better soon.