Your pet might just be adjusting to having eye drops and squinting can be normal for a very short period after. If the pain and squinting is persistent this may be a reaction to the eye drops and we recommend stopping the drops and contacting the clinic during opening hours. If you are concerned, you can apply artificial tears from the chemist such as Systane, HyloForte, or Blink Contacts tears to the eye to help soothe the eye and flush out any irritants.