Is it safe to feel turned on and do oral sex after cryotherapy?

Probably not yet: If your cryotherapy was just in the last few days, i would hold off on any oral or penetrating vaginal sex until you are more healed - you don't want to introduce infection and complicate matters. Being turned on, however, and "taking care of business" in all other ways is probably just fine (masturbating, vibrator, external stimulation).