Cold sore (Herpes Simplex Virus): This is a common condition that causes small, rounded, and often painful blisters or marks near the lips, typically occurring in clusters of 2-5. The fact that there are 3 marks and they are rounded supports this diagnosis.

Acne: Although acne can present with various types of lesions, including papules and pustules that might appear rounded, their distribution and the presence near the lips could fit this description.
Folliculitis: An inflammation of the hair follicles that can cause small, rounded bumps or marks, especially if shaving or other forms of hair removal are involved.
Keratosis Pilaris: A condition that causes small, rough patches on the skin, which might appear as rounded marks, though it's less common near the lips.

Lip Cancer or Skin Cancer: Although less likely given the description of rounded marks, any new or changing skin lesions, especially near the lips or on the face, warrant careful examination to rule out malignancy.
Infectious Diseases (e.g., Impetigo, Cellulitis): Certain bacterial infections can cause skin lesions or marks. While the description doesn't strongly suggest these, they are important to consider due to their potential for serious complications if not treated.

Molluscum Contagiosum: A viral infection that causes small, pearly, or flesh-colored bumps, which could be described as rounded marks. It's contagious and more common in children but can occur in adults, especially those with weakened immune systems.
Sarcoidosis: A condition that can cause small, rounded bumps or lesions on the skin, among other symptoms. It's less common and would typically be associated with other systemic symptoms.