The integration of Electronic Medical Records (EMRs) into the healthcare industry has revolutionized patient data management by enabling the storage of highly sensitive information. However, the continuous exchange of this information among health institutions to ensure accurate patient care introduces significant challenges related to data dissemination and security. Blockchain technology, with its inherent properties of decentralization, immutability, and transparency, offers a robust solution to these challenges, facilitating secure and efficient data sharing among stakeholders. In this paper, we present MedBlockSync, a robust blockchain system designed for improved data integrity across multi-institutional healthcare organizations. The framework is developed to achieve three key objectives: (1) safeguarding EMR data against cyberattacks, (2) enabling seamless and secure sharing of healthcare information among various stakeholders, and (3) facilitating Internet of Medical Things (IoMT) communication, including real-time data transmission from smart sensors to the blockchain network and EMRs through a secure channel. By incorporating advanced security features into EMRs without necessitating modifications to existing digital health infrastructures, MedBlockSync enhances interoperability among healthcare systems, ensuring both scalability and adaptability in the digital health landscape.