Being ill can negatively affect the health of your baby, whether you have already given birth or if you are still pregnant. You must be careful to get enough rest, eat well, and try to be happy. All of these things can affect your baby.
In regards to your baby's health:
Most baby illness can be attributed to an ear infection or a cold. But their symptoms are so much different than ours that we get scared. It is normal for them to run a higher fever than adults, but it will never hurt for you to call the doctor just in case. You will be able to rest better knowing that your baby is OK.
In regards to your health:
Take care of yourself, mentally and physically. You are probably aware that post pardom depression is very common. Keeping yourself happy can prevent this. Make some time for yourself. It can be hard to leave you baby for the first time, but believe me when I say it's necessary. You and your baby will be happier if you enjoy yourself once and a while.