You are on the right track by looking for a colorectal surgeon (CRS) as you definitely want to go to a doctor that deals with these kinds of issues all day, every day.
At your appointment, the CRS will do an examination. They can often make a diagnosis by inspecting your anus visually; however, the doctor may have to use a small scope to get a better look. If you are too uncomfortable for an examination, your CRS may recommend an examination under anesthesia (EUA). This will allow your CRS to get a close-up view of the affected area.
There are many things that could cause a fistula - a fissure that heals incorrectly, a previous cyst that bursts, a previous absess, etc.
In most cases, a fistula will require surgery to completely remove the fistula. The extent of the surgery will depend on the extent of the fistula. Some fistula's are superficial -meaning they don't connect to anything - and these are the easiest to remove surgically.
If you have a fissure, your CRS will likely start by trying conservative measures (i.e., prescription medication like Nifedine or Diltiazem, fiber supplements, lots of water, hot baths, etc.). Conservative measures work about 75% of the time (according to my CRS). If they don't work, you may want to have surgery which will allow the sphincter muscle to relax so the fissure can heal properly.
Once your CRS has determined exactly what you have, you can begin to discuss your options.
I know it can be scary, but one of the great things about this forum is knowing that you won't be going through it alone. There is a whole community of fellow sufferers who are here to help in any way we can.