I have a small lump on my forearm that breaks open and leaks clear fulid... what should i do? should i be worried that it is cancer?

Very : Very difficult to answer this without a picture. Depends what it looks like, how long it has been there, your risk factors, the characteristics of the lesion such as size, shape, firmness, color, etc...I would recommend you have this evaluated. The most common skin cancer is a basal cell carcinoma but melanoma is the type of skin cancer that can spread internally so you should get any changing or suspicious lesion evaluated by your primary care doctor or a dermatologist.