<s>[INST] Hello. My three year old son has a cyst on his right butt cheek. It started out as a bump but I noticed this morning that it is now a little bigger and it has gotten hard. I have tried a warm bath for him but what else can I do? I don t want to run to the hospital for every little thing. [/INST] Hi, it is nothing alarming, but you should get it checked by your Doctor or a Surgeon. Only by examination would we come to know what it is. It is very difficult to comment upon what it is without examining it. You don't need to worry it does not seem to be anything serious as it would most likely be a Sebaceous cyst or a Lipoma. But it would be better to get it examined by a professional. Take care, Chat Doctor.  </s>