### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
I have a large what I think is a sebaceous cyst in the middle of my back. I ve had it for a few months. The past month it has gotten bigger (ping pong ball size) and it is sore. Today I rubbed it and some clear and then slightly bloody liquid came out. What should I do to treat it? Thank you

### output:

Hi, Dear,Thanks for your query to Chat Doctor virtual Clinic. I studied your query in all the details put forth by you. I understood your health concerns. Cause of the health problems you queried-There are many causes of the lump in the middle of your back-like Sebaceous Cyst(with a central puncture or pit)/chronic Boil with subacute/asymptomatic lump/Epidermis Cyst/Fibrous/Lipoma etc. As the clear fluid came out of it with bloody liquid coming out later on, it is to be worried and needs to be ruled out for the tumor possibility and Hence I would advise you to consult ER Surgeon.-Cause of such a lump which got sore after rubbing, seems to be Sebaceous Cyst, which got clear fluid from the rubbing trauma with blood in it, which caused clear fluid with blood in it. But it is necessary to rule out other causes of such back lump.Also, I don't have any first-hand information or a photograph of the part. So I suggest you to consult ER Surgeon, who would rule out other causes and would treat it according to the cause of this sore lump in the middle of the back. Remedy-So till the time you consult ER Or tho Surgeon and get his definitive opinion after above investigations, DONT WORRY AT ALL but you need to be worried as it would complicate into some infection and other problem associated with it.In the meanwhile, Cold Compresses to reduce any swelling rise. Take Anti-inflammatory Chat Doctor.  Hope this would resolve your query with full satisfaction. Welcome for any further query in this regard to ME by direct question at Chat Doctor. Write excellent review and hit thanks, to narrate your experience, which would improve my rating for many other visitors to Chat Doctor. Wishing you fast recovery. Have a good day.