Over dieting and exercising and getting sick

I've been pretty disciplined in the last month or so about eating right and exercising. Eating right doesn't always mean 100% nutritionally balanced foods, it usually means mostly healthy for me and not putting me over my calorie intake for that day. I admit I've scrimped on my food a couple times to make room for some late night snacking.

Right now I am working around a 1200 calorie goal per day. Lately, most days, I go over that. I either break even after my workout is calculated or I am even slightly over that.

However, it feels like if I don't stick to exactly 1200 or slightly under, my weight creeps back up. At the same time, I seem to be more prone to getting sick with chills and low grade fevers. It's very confusing. Am I deprived or what??

My body is feeling a little run-down just now but I am afraid to start kicking up the calorie intake, in fears of setting myself back a few pounds. Also, it's been hard to limit myself to only things like salads and fruit and all, even though I know it's better for me, because I feel so hungry for more dense foods. I'm not starving feeling, just craving comforting stuff.

...also, I want to keep working out though everyone at home has told me to take it easy for a couple days or I'll get sicker from not resting. Will the sweating and exertion make me worse? Stupid question probably.