I am on 10mg fluoxetine for 4weeks now. Two different pharmacists said melatonin for sleep issues I am nervous is it ok to take it.?

No problem. Your pharmacists told you right. There is no problem taking these medications together. Best wishes! P.S. You are wise to ask before you swallow.
Melatonin. is what I provide to my family for problems with sleep. It has a good side effect profile and can be quite effective.