It may not have come to your attention that there is usually a BIG difference between online marketing locally versus marketing nationally.
This is kind of obvious in traditional advertising. A TV commercial on the CBS Network is going to cost more than one on your local CBS station only. An ad in a local magazine is going to be way cheaper than one in Vogue.
The same is true online.
The reason is COMPETITION.
Competing on the subject of "allergy relief" in your local area, you are primarily going up against other local businesses. Trying to compete nationally, your competition is large, national organizations that may have many full-time staff working on their website and Internet presence.
Of course if you are in a tiny niche field - an online store that sells snail farming supplies - there isn't going to be a lot of competition even internationally.
But if that isn't the case, competing on a national basis is a whole different level of game.
A major reason for this is SITE SIZE. In competitive national search areas, it is not unusual for top-ranking sites to have 10,000 or more pages.
So you need a strategy for building a big enough site, fast enough and cheap enough that you can afford it.
Otherwise, don't even try it. Play a game you can win.