Nightmare child

I did write a post yesterday but i need help with why my baby might be acting up. She used to be such a good sleeper and out of nowhere its like someone swapped my child. At about 7pm she starts getting irritated like shes tired but shes not. She will cry and cry and scream until gone 9pm.. she hits and kicks me if i try and hold her and she hits me and hangs off my legs if i put her down, she does this for the full 2 hours when she doesnt need feeding or want milk or water, shes not hot or cold, her nappy is clean and if i think shes teething she has medicine and NOTHING works i just have to deal with it and its horrible. Im seeing a doctor for her tomorrow but i just want some opinions. Shes 8 months