What Causes Diarrhea Along With Sore On Outer Anus?

I recently returned from a trip to India. I had diarrhea while I was there for about 5 days. I believe it s from drinking too much whiskey (alcohol does that to me). Regardless I have a sore just outside my anus. Is it common to get sites from diarrhea or should I have it looked at? It s about the size of a dime.