I got this runny nose that dosent go away its been 3 month what should i do?

Allergic rhinitis: Is runny nose worse in any particular environment? If so, can you avoid that place? If not, try OTC antihistamines. Loratadine is least likely to make you sleepy while diphenhydramine is most likely to do so. I couldn't find nasal antihistamine spray available OTC in States. Nasal steroid sprays fluticasone & triamcinolone are available OTC w/o prescription. Avoid nasal decongestant sprays.

It may be allergyl: This is unlikely to be infectious alone, but it may be allergy. You could ask your physician to evaluate you, and consider having you see any ENT physician or an allergist. There are some simple medications that can be used for allergic rhinitis which this would be the diagnosis

Chronic: Chronic runny nose could be allergic rhinitis . See your doctor , and try some antiallergic medication. You may also get evaluated further as to what you may be allergic to.