Is Falling Ill After Istikhara a Sign From Allah?

Walekumussalam 

Just falling ill during the exam period and recovering afterward is not a definite sign that gynecology is not the right specialty for you. The purpose of Istikhara is not necessarily to receive a dream or an unusual sign; rather, it is to seek Allah’s guidance and blessing in making the best decision.

Therefore, base your decision on your interest, abilities, circumstances, and practical opportunities. If you still feel that gynecology is a good fit for you, there is nothing wrong with pursuing it again. Do not regard this illness alone as a clear negative indication from Istikhara. Continue making dua, seek Allah’s guidance, and consult knowledgeable and experienced people as well.