About 2 weeks ago i couldn't stop coughing and getting fevers. now my singing voice has changed and everything i sing my voice cracks. how do i fix it?

Rest your voice: You probably have some inflammation of your vocal cords. I would rec. Resting your voice for at least two weeks-- no singing. If you sound hoarse when talking, then rest it with speaking also. Whispering actually makes it worse, so just write or text. If you still hear cracking after two weeks, see your doctor for an exam of your vocal cords.