11 year old boy.. Abnormal behavior?

My little brother will be 12 soon.. He's still exhibiting some behaviors that concern me. For one, he cries a lot. He cries when he's frustrated, when he's tired, when he gets in trouble, when he's asked to do something he doesn't want to do, etc. He often says he's ill. Probably 3-4 days a week he complains of nausea, headaches, or just feeling bad. Several times a year he goes to the school nurse with complaints and asks to be sent home. Our mother has migraines fairly often and calls in sick because of them, he sees this and does the same. Our mother had a lap-band surgery last year and has difficulty eating some foods. She has specific complaints when she's having trouble eating and the complaints are very specific to the surgery. My brother has been using the same complaints. My brother exaggerates stories all the time (I'll give him the benefit of the doubt and assume his stories are partially true). For instance, my husband and I were talking about raccoons and my brother chimed in with a story of how a boy at boy scout camp with him slept all night with a raccoon, but was unaware. Any small spider he sees becomes the size of a baseball. He said he was trampled on the playground at school by all the kids in his class. Says my 13 month old daughter is saying words she's incapable of, like "volleyball." He copies pictures and passes then off as his own artwork. I've spoken with our mother about this and she pretty much just blows me off. Am I worrying unnecessarily or are these behaviors cause for concern?