First of all...calm down
. Ick is not the end of the world and quite common. The good thing is you caught it early. You don't need a heater (especially not in a 1/2 gallon...you'll fry the little dude). While some may say raise the temperature to speed up the ick parasite's cycle...actually you don't really need to. Some fish don't take well to sudden, large shifts in temperature. Just follow the directions that came with your Quick Cure (and if you have questions, just go to the manufacturer's website...it'll have dosage info, etc. And you can email them w/more questions if need be).
My first betta, Solomon, got ick not too long after I got him. I used Cure Ick by Aquarium Products (I believe the same makers of your Quick Cure). I gave him 3 dosage cycles over the period of a little over a week (read up on ick using your search engine or posts about it...you'll find that when the white spots disappear is your real window of opportunity...it's then that the parasites leave the fish's body and go down into the gravel to multiply then they'll try to reinfest the fish and start the cycle all over again) and he's all better now. Back to his active, happy self and making bubble nests.
Now that he's cured, I use Aquarisol in the water after his 100% water change that I do once a week (I also do a 25-50% change mid-week). The Aquarisol works as a preventative. And when Solomon got sick I immediately started using it in Samson's tank so he wouldn't get it.
I've read a couple of places that once a fish makes it through a first bout of ick that they sometimes develop immunity to it. I have no idea how true that is or not.
Just keep treating Citrus as directed and keep an eye on him. And use gloves while he has it, your medicating him and coming in contact with his water. I don't know about Quick Cure, but Cure Ick has some toxic, carcinogins (ok...I know I totally misspelled that) in it.
Keep us posted on Citrus.