21 month old has been lethargic and irritable for 5 days. complaining of body and teeth hurting, not much appetite, but no fever. is it serious?

Flu like illness: Your child may have a flu like viral illness. Since its been going on for five days a visit to your child's pediatrician is in order

2 possibilities: One possibility is a viral infection, such as a cold. The other is a bacterial infection of the teeth. Your child should have been seeing a Dentist since his/her 1st b'day. Call for an evaluation. Also call the Pediatrician and report symptoms as an examination may be in order. Make sure to keep child hydrated.

Monitor temperature : Monitor temperature, encourage fluids and please see your physician right away. She may have a viral illness or another condition. Watch for lack of coordination, problems breathing or swallowing.