"Chemo brain" is an urban myth. Typically chemo agents can't cross the "blood/brain" barrier. More than likely it's due to weakness from malnutrition, poor hydration, constipation and/or pain medications. I had a number of dizziness/fainting spells in the late Tx and early post Tx stage and it is very common. The inner ear can get clogged up with fluids and also cause balance problems. One must be very careful when standing up or getting out of bed. One thing that helped me was to sit upright first, for a while, before I got on my feet. He should ask for help. A walker might give him even more stability. He certainly does not need a broken hip.

You are wise to stay away while you are sick. Exposure to a common cold could easily give him pnuemonia.