Urgent Advice Needed

Can anyone out their give me any tips on how to cure a sore thigh! I think I have
over stretched last night,before my training?I did put on some oil of wintergreen
last night?But came to work this morning and its still sore?

I am also running my first half on sunday!!Starting to get a bit worried!! Do you also
suggest maybe apply this before my run on sunday!!

Any advice from you foks out their,would be greatly appreciated.
Bye for now
flipper