How can one get rid of the waswas (obsessive whispering) that focuses on doubts about purity, acts of worship, and the acceptance of repentance, and leads to repeatedly checking matters, along with feeling watched, social isolation, becoming agitated with parents, and refraining from visiting relatives due to family problems; and does hearing an internal voice indicate an abnormal condition?

You must cast away these whisperings (waswas (definition)) and pay no attention to them, for they open a door to evil. You can seek help through prayer, worshiping Allah, and remembering Him. You can also consult a specialized female doctor and the consultation section on this website. Seek Allah's forgiveness for shouting at your parents and strive to please them. As for your grandmother, if visiting her causes harm, there is no sin in not visiting her, and you can maintain ties with her through phone calls or similar means.