What is worth more to you: your roadtrip or your leg? Sounds like an abscess/infection. As someone else already noted, you are exhibiting classic symptoms. Infections in the muscle bed are extremely serious. I am not exagerating when I say you could lose your leg. Get thyself to a doctor yesterday! Fuck the roadtrip! They will likely culture the bacteria in the abscess to classify it so they can prescribe the best antibiotic. If you are lucky, they will lance it and put you on IV antibiotics for a few days. If you wait too long...........
Spidey is a fictional character. I do not use or condone the use of illegal drugs. Any references to steroids or other illegal drugs is purely for entertainment purposes and role-playing.