We are sorry to hear of your need to isolate.
You assume correctly that you may not immerse until your period of isolation is over. Niddah status remains in place until after mikveh immersion.
In the meanwhile, you should complete the clean days as usual. When the night on which you had planned to immerse arrives, you may switch to colored undergarments. No further bedikot are necessary from that point on, and you may immerse the first night following the completion of your isolation period.
If it is relevant, you may wish to consult your physician about extending use of active pills in order to ensure that you will not be in niddah at the end of your isolation.
We wish your husband a refuah sheleimah! Please let us know if we can be of further assistance.