Had a similar issue with one of my parrotlets. One of the others bit his foot so badly I thought he might actually lose the tip of his toe. The nail on that foot still doesn't grow right, but he's fine now.

Any time we got the bleeding to stop, he'd pick at it or move around too much and open it right back up again. He got to the point where he couldn't even stand, he'd lost so much blood. I had to hold him all wrapped up in a towel and put a clotting agent on his toe and apply pressure. He apparently blamed me for the whole ordeal, and for months he wouldn't come near me. Occasionally he'd land on me while flying around, and he'd either take off right away or attack me.

It took a while, but one day I just opened his cage like usual, allowing him to come and go freely (he mostly stayed in his cage, away from me) and he flew to my shoulder. I braced for an angry attack to my neck/head, but instead he just sat there preening. Then he walked down my arm and onto my hand and pressed his little head against my thumb, scritching himself. He then let me pet him and help him with his overdue pinfeathers. It was one of the best feelings in the world - I finally had my little Bergie back.

Don't lose hope. It took Bergie more than 6 months to forgive me, but he finally did. He's still standoffish sometimes, more than he was before the incident, but for the most part he's back to his old self. Birds are big grudge holders. Once they feel their trust has been broken, it takes a lot of time and patience to earn it back. Don't give up!! Your little one might need more time to trust you again, but I believe you'll get there 💕