Cellulitis or Soft Tissue Infection: Given the patient's history of a splinter that has been present for 2 weeks, attempted self-removal, and subsequent signs of infection (pain, color change to white and green), this is the most likely diagnosis. The presence of a foreign body (the remaining splinter piece) increases the risk of infection.

Abscess Formation: The patient's symptoms of pain, especially with pressure, and the color change could indicate the formation of an abscess around the retained splinter piece.
Foreign Body Reaction: The body's reaction to the foreign object (splinter) could cause inflammation, pain, and potentially lead to an infection.
Paronychia: Although less likely given the location on the foot, if the splinter is near the nail bed, paronychia (an infection around the nail) could be considered.

Osteomyelitis: Although less common, if the infection has spread to the bone, osteomyelitis could be a life-threatening condition that requires prompt diagnosis and treatment.
Gas Gangrene: In rare cases, especially if the patient has a compromised immune system or the wound becomes infected with certain bacteria (e.g., Clostridium perfringens), gas gangrene could develop. This condition is medical emergency.
Tetanus: Given the patient's occupation and the nature of the injury, tetanus infection is a possibility, especially if the patient's tetanus vaccination is not up to date.

Erysipelas: A type of skin infection that could present similarly but is less common and typically has a more distinct border.
Deep Vein Thrombosis (DVT): Unlikely but could be considered if the patient presents with swelling and pain in the leg, although the presence of a splinter and localized signs of infection make this less probable.
Mycetoma: A chronic infection that can be caused by fungi or bacteria, typically presenting with a swelling that can discharge sinus tracts, which is rare and usually seen in tropical regions.