Bump on thumb. What is this?

Im attaching a picture of my thumb. So i have a very small hard lump inside my thumb since childhood. It dint bother me much. The skin on top was always normal and i was able to live normally. But since a month the inside lump i feel grew a little and almost around the inside lump i see this yellow appearance on top of thumb currently. Went to dermat last week, she said its a corn and gave me salicylic acid cream which i used for few days but no improvement. The yellow thing is slightly just growing. I went to ortho today. Took xray it looked normal. He said use the salycylic acid cream few more days. Im really not happy with the diagnosis because i dont think its a corn at all. It does not pain on its own. Only discomfort, slight pain when i do something that puts pressure there. The inside lump since childhood is causing these issues now i feel. Please guide me anyone. What is this? Do i need to go to a dermat or ortho or hand surgeon.