Is self pay really that bad?

For context, I work on a tugboat moving barges. For the most part, I have managed my back pain (I think I have herniated a disk) throughout the initial orientation period. Today’s tasks were spent bent over for the majority of the time and my back is in pretty killer pain, about 6-7/10. Ended the day about 3 hours ago and my back is aching and moving around is just painful. I do not believe this is a tenable position given the physical nature of the job. My health insurance through the job doesn’t start until 90 days in and I’m afraid that even asking if that period could be waived would lead to a loss of employment. That’s the worst case scenario, best case it’s no problem. That being said, is paying for a visit, imaging, and a cortisone shot really that expensive vs waiting for the insurance? I didn’t realize that I couldn’t just… purchase health insurance whenever (I’m 24 and have always opted into employer plans, so I’ve never been without insurance) and I don’t know what to do. I just feel… helpless. Thanks in advance for your advice. EDIT – Age: 24 State: VA Gross: 40k (just started so low income?)