Not eating due to lack of appetite and being under the weather.

I’m mid 20’s, 5’8, about 150lbs. For the past month or so I haven’t been eating much. I’ve been intermittent fasting for years. Only eating between 12-6ish. My lunch appetite started getting small but I would eat a normal dinner. However, in the last week and a half or so, I have only been eating about 500 calories a day. (I have been pretty under the weather with all the holidays and change of temperatures which may be playing a role.) I just don’t have much of appetite and get full quick. Come dinner time, I’m not even hungry and just go to sleep. I’ve always been active and do some light cardio everyday to due my job.
Can this cause health issues? Or should I just count it as a blessing?