I Have A Bump On The Inner Of My Thigh

I have a bump on the inner of my thigh by the groin, it is painful swollen and no a streak is going up my leg and is swollen also. I am not wanting to go to the dr so I have taken antibiotics called flagyll that I have gotten from a friend? Do I need to go to dr are wait and see if this medicine will help. I have had the knot came up about 3 days ago and taking medicine starting yesterday/ What do I do? Thanks