(1) It is allowable to keep the chillies in the cold storage after purchasing it and to sell it later if the local people do not face any problem in getting the chillies and the rate does not go high. Write the complete text of the hadith referred by you with the reference of the book, then we can have a say in this regard.
(2) The advice of the doctors that there is no cure for it is based on their ignorance and lack of knowledge. Almighty Allah has created the medicine of every illness, but it is possible that we do not have access to them. So keep on doing dua, we too shall make dua for you. Also, keep on treating the illness as per your capacity. In-sha-Allah, she shall be cured fully.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband