Okay, so my bearded dragon is 3-4 months old. I have noticed yellowing before and I did take him to the vet. I was told not to worry too much about it and put 1:1 water to betadine solution on it. It went away slowly. Was completely gone when shedding. Took him to petco (that is where I got him) and they said he is perfect healthy. He already lost a finger due to improper shedding when he was at the pet store. Anyways, the yellow is back in the same spot. On his spikes down to half of his stomach on his right side. It’s a bit larger now too. He’s too small to get a biopsy of it. And was told medication can be worse than YFD alone. Please help.
I don't think that is yellow fungus, but probably some skin that is older & needs to shed.
However, you can be proactive & get some topical anti-fungal cream to use on that area,
such as lamisil or monistat. Apply that daily to see if that helps out for the skin.
Let us know how he is doing.