Doxycycline is a semi-synthetic tetracycline antibiotic prescribed to treat various bacterial infections such as urinary tract and bladder infections. Veterinarians also use Doxycycline to treat some diseases such as Rocky Mountain Spotted Fever and Lyme disease.
Habituation is actually a good thing; it indicates that the child is learning. For example, when there's a loud noise, Parker is startled and looks at whatever makes the noise. He is scared that the loud noise might mean danger.
Habituation is when an animal is presented with a stimulus and responds to this stimulus, but when the stimulus is presented repeatedly with only a few minutes or seconds between it soon stops responding to the stimulus because it has learnt that it will not harm or benefit the animal so it has learnt to ignore it.