Can a mole turn into basal cell or squamous cell carcinoma? (Photo)

I finished a 21 day Efudex treatment on my chest yesterday and noticed a change in these moles. Ive had them at least 7 years. One of the moles shrunk by half and the other two are inflamed. I have other moles on my chest and they have no change. I have a history of squamous cell and am extremely concerned. I'm almost positive the one that shrunk by half is skin cancer. Can a mole turn into basal cell or squamous cell or is it possible it was skin cancer all along?