to the question -it is normal to eat at night? - yes it is normal, they're nocturnal and have to be fed after the lights are off. what size is your frog? and welcome to the forum by the way

as for the rest, there is a questionnaire in a sticky thread in pacman section, would you please answer those Q and open a new thread in there so we can help you better.
you will need to get temp gun or gauge or something to know exact temps, what you're saying is not reliable in measuring temps and lower then needed temp will cause a frog to slower it's metabolism down and not eat or eat less.