hello and welcome to HCM,
Let me mention to you some basic facts and clear your doubts if possible:
1. FESS is a surgery done only to clear sinus pathology and nothing else. If you have headache before surgery which is due to sinusitis
that is the only symptom that is relieved by FESS and no other symptom is relieved by FESS.
2. If you have nose block then a combination of FESS and a surgery called SEPTOPLASTY
has to be done to relieve the block. Here again nose block is the only symptom which can be cured by the said surgery.
3. If you have runny nose and sneezing then you have allergic rhinitis
for which the cure is allergy avoidance and anti histamine
medications for control.
Now looking at the above points you need to decide on what is your primary symptom and decide according to the same.
Meanwhile if you can mention the latest CT and endoscopy
report then i can help you in making the decision better
Dr Sriram Nathan