I definitely think the hard water had a lot to do with it for me! I don't have nearly the struggles with my scalp since I moved last year.
I used this filtered shower head. It didn't remove everything, but I noticed a substantial difference. I replaced the filters about every 4-6 months, and could always tell from the way the water felt that it was time for a new one.
I used to take Xyzal, and while it was incredibly effective, it made me ridiculously drowsy, was often hard to find in the store, and I think it slowed my metabolism so much that I was gaining weight. I'm pretty sensitive to allergy medicine though, so I eventually switched to Zyrtec since it has the same active ingredient as Xyzal, with less symptoms. I take it year-round, and split the pill in half.
I hope you find relief soon!