I think u have fungal problem.
Check any more soft pseudobulbs or not first. Then divide soft one & good one using sterilize knife. If not, the disease will spread & all pesudobulbs will be gone. Immediately throw away soft pesudobulbs to prevent from spreading to other plants.
After dividing, soak good bulbs in fungicide solution(you may buy either Captan or Physan) for about half an hour. Then keep in bright shade with good ventilation. Every three days spray with fungicide for about two weeks to a month. During this time keep it on dry side as too wet condition will promote fungal problem again.
Hope this helps.