Well, in short, according to 21 CFR 73.2150 and 21 CFR 70.3v of the FDA regulations, DHA is restricted to external application only when using sunless tanning products. This means no lips no inhalation from sprays just medicals bad and fake simple topical additions.
And a greater part of medicals fake the issue is all those products bought were with the idea that the cure was just about to happen the next day or at the very latest next week. You didn't get to the point of being unhealthy yesterday or last week, but the good news is it won't take you as long to undo what it took so long to accomplish, if you want to call poor health an accomplishment.
Back in the 1970's, DHA was approved by the FDA. Keep in mind this was only for topical applications, because who would have thought people would spray a fine mist years down the road. The development of issues started to arise thanks to the contact with the lips, lungs, medicals bad and fake other sensitive membranes, which of course meant it went to people's blood stream.
Tooth and gum problems provide a perfect breeding ground for anaerobic bacteria that are responsible for breath odors in more than 90% of all people who suffer with a bad breath problem.
Just avoid them all together. The booths, the lotions, the topical cream or anything else that could possibly contain harmful ingredients should be avoided.
A last practical suggestion: If you have access to one, bring a portable game device (even a phone) or DVD player. Studies show that children who are engaged in watching something they enjoy perceive half the pain or less during a medical procedure than children who are paying attention to the procedure. Even a beloved book may work to take their mind off the vaccines.