Just learned I make 13k less than a coworker who does much less work than I do. How do I handle this?

A coworker of mine (who is awesome, no fault of theirs or anything) got hired a few weeks before me and makes 13k more than I do doing much less work than I do. I feel like I shot myself in the foot during negotiation. I’m awkward at negotiating, they asked me my salary range. I said 55-65. They offered 55. I just feel pissed. Feels like a punch to the gut. I like the job but I only started a few weeks ago. I have a 90 day trial whatever to get started, for context. Any idea how I should handle this?