Like you, I have not only the fourth toe, but also two big toes. I looked up a lot of information on the internet, and I didn't know it until now.

The technical term for this disease is congenital metatarsal short. When the patient was born, his toes were normal. Generally, at the age of 7 or 8, the epiphysis of the fourth metatarsal closed prematurely and stopped growing, while other toes developed normally, and the fourth toe was short and deformed in adulthood.

If you want to correct it, you can do external fixator combined with osteotomy to lengthen the metatarsal bone. I don't know where to start here, but I'm still scared. I hope to have medication, but it should be physical reasons. I don't know if you found it.