There is a new product called NozAmi that is specifically designed for longer lasting relief. I used to get nose bleeds all the time and then my doctor gave me a trial of this stuff... I've been buying it ever since. It really works much better than saline and water treatments.
I am not a doctor, but I have had this same problem. It happened to me when I moved into a dorm. Must be their air system or something. I would get scabs up in my nose and it was so gross. I used vaseline, and it did help. But humidifiers would definitely help long term.
There is a nasal gel product for this called Ayr. There may be similar, in a different brand.
You need to drink plenty of fluids and from the sounds of it, benefit from having a humidifier. In the meantime, can always put a large pot of water on the stove and let it simmer.