That's not a hairball! It's actually a cough.
Many pet owners mistake their cats cough as an unproductive hairball. What most pet owners don't know is that many cats suffer from allergies and even feline asthma, so all that unproductive coughing could actually be an asthma attack. Something you should definitely have checked by your vet. Rest assured there are treatment options to help your kitty with their asthma.
Inhaler demo using the AeroKat delivery system.
Demo on how to give sub-q fluids at home.
Placing your cat in a top opening carrier while giving fluids greatly helps to keep them on one spot. If your kitty moves and the needle comes out just stay calm and turn the flow off. Put on a new needle and poke again. You will want to use a new needle each time. Dr. Munck has approved reusing the line/drip set for 3 bags and then you should replace it.