3 doctors agreed: Muscle spasm: This could be a muscle spasm. I have heard this description many times before. Hernias do not occur in the upper abdomen by the rib cage. They do occur in the middle. The muscle spasm can cause severe pain, and ball up, mimicking a hernia.
Generally, working part time is considered working anything less than what your employer considers full time. The Bureau of Labor Statistics defines part-time status as working on average between one and 34 hours per week. In the end, it is up to the employer to decide how many hours is part time and how many would make the job a full-time position. The Department of Labor does not differentiate between the two statuses.
Part-time Employment. Part-time schedules may be established when the workload will not support full-time employment or when an employee asks to work part-time and the request can be accommodated. A permanent part-time employee may not work less than 16 hours or more than 32 hours in a week.