I have a giant painful blister from a ant bite. what should i do?

Insect bite: Blister may rupture on its own. If you have surrounding redness and warmth may be an indication of infection. Once the blister opens the underlying red base will heal, Just keep it clean and may be some topical antibiotic like neosporin might help.

Observation: Ant bites will typically resolve without treatment, but if there is increasing blister size, or redness/pain/warmth at the site a medical visit would be prudent idea