If the ankle feels fine, you likely did not fracture the fibula. Ice it tonight, 20 min on, 20 min off for several cycles and see how it feels in the morning. If greatly improved, you probably did not injure a key structure. For me to comment much further in this venue without knowing much more would be ill advised.
if seeing doctor Monday, not much other than ice and Motrin/ibuprofen. twisted my knee 3yrs back, too "manly" to take a ride down and in earnest, just this yr feel a bit normal but I never saw my doc or did any PT. So, advice is get a good checkout and invest in some PT ....
gastrocnemius? apply/pinch pressure to achilles which is the bottom part of the gastronemius. if there is movement then not a tear. had this injury last month. it took 2 weeks before i could walk or ski. good luck.