Hi, welcome to the forum, clear running nose can be due to allergic rhinitis. It usually increased in winter season. Other possibility is vasomotor rhinitis which occurs due to rapid temperature changes. In 50% cases of allergic rhinitis is associated with asthma. The rhinitis can be triggered by specific allergen like pollens, dust etc. You need to go for allergy test if needed to rule out the allergen. Avoidance of exposure to allergens with nasal decongestants will be helpful.
Another and strong possibility is CSF (cerebrospinal fluid) rhinitis, this happens due to leakage of cerebral spinal fluid and can result from skull or nasal fractures, intracranial surgery, and inferior extension of sellar masses. CSF can be distinguished from local nasal secretions by the presence of beta-2 transferrin, and when the CSF fluid comes in contact with hanky, it becomes stiff after sometime. I suggest you to consult ENT specialist. Take care and regards.
It sounds like allergies to me. It could be from pollen, mold, dust, just about anything, and allergy meds should take care of it pretty easily. Yup, this is fairly common for this time of the year and even tho you may not have ever had this before, it can make its self known at any time. Check with yer doc to make sure, but it sounds like simple allergies to me.