Hi EarlyTwenties,
Sounds like it could be a couple of things. If you removed the unit too quickly without allowing the rubbing alcohol or Lace Release to fully dissolve the adhesive you might have irritated your scalp. Ultra Hold is the strongest glue available and it needs extra time to break the bond. This would be a temporary situation. The other thing is you could have had an allergic reaction to the Ultra Hold. Have you used it before? Any reaction? We always recommend that people test a glue on a small patch of their skin before using it to see if there's an allergic reaction. I'd give it a couple of days to see if it goes away.
Regards,
John