I should add that in addition to the rinses, I use a sinus medicine that helps tremendously! (link below) Make sure to use the night time version. The regular non drowsy versions do nothing for me, even at prescription strength. I normally get it from Costco but my Costco has not had it in recent months but luckily its on Amazon. I am sure though that you can get something similar at the grocery store. There is a very small amount of antihistimine in it (just 2mg, not enough to make me tired) I have been tested for allergies and I do not have any btw. I know of several other people who swear by this stuff for sinus related issues. https://www.amazon.com/gp/product/B00FVOWA76/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
So my headaches we not one sided but the since sinuses are separate chambers you can have the bacteria in one but not in the others. Mine started in the forehead sinuses, then moved down to the ones below my eyes and then months into my illness moved into the sinus chambers behind my ears.
As to the neti pot, I've never used one but my understanding of how they work is that there isn't any water pressure involved so I would think that it wouldn't work as well as the Neil Med rinse which is a squeeze bottle and able to get up into the sinuses better.
These are my favorite pain relief pills. You can get them at Costco but here is the link to them on amazon. The box has daytime and nighttime versions, its the nighttime ones that work really well. For me at least, they don't make to very tired at all even though I tend to be really groggy after taking just a Tylenol PM.
https://www.amazon.com/gp/product/B00FVOWA76/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1