New condition while awaiting appeal for first refusal

Client is awaiting tribunal hearing having failed initial medical.  She is in receipt of the assessment rate of ESA pending her tribunal. 

She now has a new condition as was hospitalised for 2 weeks because of this.  She is now out of hospital and I advised her to send a copy of her hospital discharge note to ESA as evidence and ask for a new assessment.  She has done this. 

I am now concerned that maybe she needs to make a new claim rather than notify ESA of the change of circs, which is what she has done. 

Does she need to make a new claim? 
If so how will she do this, as the new claims section are likely to tell her she can’t as she already has an existing award?

For someone in this situation is there a tactical argument for doing nothing until the ESA appeal is decided?  Then, if the appeal is not successful, make an immediate claim on the new condition.  If it is successful, hold it in reserve if necessary (Of course this depends on whether the new condition is a long-term one).  Ruth