Why do my lash extensions suddenly get super itchy after 2+ weeks?

I have a question about my eyelash extensions. I got them done on May 9th, so it’s been about 16 days (around 2½ weeks). This is a photo of how they look now.

Out of nowhere tonight, my eye started itching so badly to the point where it feels red, irritated, and uncomfortable. My eyes look visibly puffy, and one eyelid looks more swollen/bigger. Does anyone know why this happens?

When I first get my lashes done, I never have itching or irritation, but this has happened a few times later on after having them for a couple of weeks. My eye gets so itchy that I end up rubbing it, and it almost feels swollen from the irritation.

It’s honestly making me want to stop getting lash extensions for a little while because it gets majorly uncomfortable when this happens. Has anyone else experienced this, and is there a way to prevent it?

Also, I had some other questions I’ve been wondering about pricing and wanted to discuss what’s normal for this service, as I usually pay $100 for a 2–3 week hybrid refill. Is that considered a fair price, or does it seem high?
Based on the retention/how they hold up, does that sound reasonable?
And does lash length affect retention?
I have hooded/smaller eyelids, so I usually get a longer hybrid set because shorter lashes aren’t noticeable on me when I look straight.