I have been having major problems with anal swelling but the swelling comes and goes. Sometimes I will have it in the morning, and it will be gone by the evening. When it is there it looks like a big lump on the outer edge of the anus. Sometimes it is so big it covers the anus!

I have been examined multiple times but the swelling has never been present during an exam. If it is a hemorrhoid that keeps swelling and reducing (if this is possible), would it still be detectable in its reduced state?
Thanks!