I have a callus on the side of my right foot but it hurts like if I have a niddle or a stick inside it?

Have it evaluated. Callusing is usually secondary to mechanical pressure(something compressing the skin against bone). A foreign body is also a possibility. See your podiatrist for evaluation and treatment options.
Fun fun fun! I have the identical same thing. Triggered by a plantar wart. Over 12-15 yrs now. There's are treatments available. See a podiatrist please.
Painful calluses. There will often be a focal spot of increased pressure in a callus, usually over a bony prominence. This will be seen as a "deep spot" within the body of the callus and gets to be quite painful. Conservative care consists of reducing the callus; add an orthotic device with an accommodation to further reduce the pressure on the spot. Surgery sometimes to correct the underlying bone deformity.