Illness in a dream rarely predicts actual sickness -- it more often reflects vulnerability, a need for care you haven't been giving yourself, or some part of your life that's fallen out of balance. Recovering within the dream can point to a genuine return toward equilibrium already underway.
If Mercury be afflicted in the sixth house, the native shall die in prison: if Saturn shall be in the twelfth, and Venus in the eighth, he shall end his days by precipitation. - William Lilly (1602.-1681.)