6 year old behavior getting worse

I have a 6 year old and for the past couple of months we have noticed her behavior getting worse. She is currently failing in school even with help at home and school, disrespecting her cousins, constantly lying (it's become an everyday thing) also as well having tantrums when told no or tantrums when you tell her to do her homework. She also starts to say she's bored when she's playing, doesn't socialize with other kids when going to birthday parties only with family she will socialize. And plays with her hands and feet or her clothing anything around her when told to do homework as well( you can remove the pencil and she will go for her clothes, feet and hands)