Can Mosquito Bites Cause Black Marks?

Hi, may I answer your health queries right now ? Please type 20 days back i had a mosquito bite on my face. i consulted a skin specialist and he told me its peadrus dermatitis.after 20 dayz... the poison is been removed, bt left side of my face is all black with mosquito scars. and after using fumlative and solset lotion on new skin and got lots pimples on my old skin. i dnt know wht the problem is. Is this mosquito bite or something and why im geeting pipmles if poison has been removed regard>Heena