Allergic conjunctivitis is non contagious only. Conjunctivitis may be infective or allergic. Allergic is non-infective. Allergic conjuctivitis can cause discharge but usually that is ropy or clear water like. Itching is commonly associated with it. If the diagnosis is in doubt, it is better to see an ophthalmologist. I hope it helps.
You are most welcome. Yellow discharge is more in favour of muco-purulent discharge seen in infective conjunctivitis which is certainly infectious. I would recommend an examination by an ophthalmologist. Thanks.