I have a couple of week-old, hard, painful lumps on my groin. should i go see a doctor, or can i get some over-the-counter medication?

Hard groin lumps: The answer is self evident. See your doctor ASAP

Lumps: These lumps are usually enlarged lymph nodes. Nodes strain your body serum to remove toxic debris including germs and prevent them from entering the blood/tissues. They could represent a localized problem on that leg or your genitals. If they are painful they are working very hard & it is a warning that they may need help. See your doc to see if you have a problem that needs meds or tests.