Hello, A Glucose of 120mg/dl is not low. Normal glucose patterns for Kids-Teens are an average 80-160 depending on how many meals they ve had and time of day. You ll have to forgive me but I do not have a full clinical picture, however I can tell you this age is certainly involved with many hormonal, personality and physical changes associated with puberty . The age 14 generally is a select few months-more of huge adjustments in a teen s body s chemistry. Your son may be starting to experience this; and thus it is showing in crazy unexpected ways. Puberty can encompass all the issues you are describing and last for what seems like eternity, but in reality will slowly but surely become more manageable over the coming months. If you truly believe something is wrong, I highly suggest you possibly have a checkup with a Psychologist and or Psychiatrist. They can very much hone in on specific psychological and even chemical issues which may be causing the symptoms you describe. As I said before, I think it may be hormones and puberty. As such a health diet, and hydration, along with encouragement can really aid in your son s development. Warm Regards, I hope this has helped.