So I’ve seen a few different discussions on this topic already but still would like to input some more food for thought. Consider this, a college junior by year with sophomore level EGN classes is considering a major change to something in medicine. Stay off the keyboard for a moment longer, this student began their career as a sport and exercise major on their way to become an AT but was dissuaded as it is a very rough career in their state and due to a number of personal factors was persuaded to switch from this major by family to an engineering field. Also consider this person’s reasoning behind their first major choice was an interest in emergency medicine and the thought that they would be helping people and that their reasoning for a switch to EGN (mechanical by the way) was that this person had a large history in motor maintenance and admittedly a fondness for machines and their production/optimization. Another possible factor to take into account, this person will be commissioning in the USAF after degree completion either way. Taking all this in to account, I would like to hear any thoughts or questions that would lead to discussion on this situation.
Is there a question in there? Who are you asking for?
How long do I have to stay off the keyboard. 
It looks like your question is about “health related major” vs Engineering. Can’t really help you with that, other than saying the student should pick their major, one way or the other. Both choices will work well with a commissioning in the USAF.
So the question is just general thoughts on a major change this late in the kids career.
He hasn’t had a career per se. Given that they will have a multi-decade career, I’d suggest they choose what they want, not what someone else thinks is best.
Is this your child?
No this is me, the student, lol just usually easier to get honest opinions when people don’t think they’re going to hurt your feelings. I (suppose I can use first-person now) began college on a Sport & Exercise track because I enjoyed helping people and solving problems, I also spent a lot of time in doctor’s offices in my high school to say the least and enjoyed the thought of helping people and general medicine. I dropped the major during a time of personal struggle and was convinced to switch to Mechanical Engineering after urging from both people in my profession advising I consider other options and my father as I had history working on motors, problem solving ,and a great interest in cars. I have only gone as far as CALC1 and at this point wonder what if any major would be a good idea to go to and if it is a good idea at all to switch. My projected graduation is 2021 and I need to be right around there for my commissioning. My major interest in medicine is triage and helping people if that helps inform any opinions on the topic.
Tinkering, and don’t take that as a derogatory term, is often confused with engineering, but it is actually far from it. What you did with cars may help inform your engineering, by having a practical sensibility to your design, but engineering is really applied math. If that still sounds interesting, you could continue, but it doesn’t sound like that’s what excites you.
There are many health related fields. You could be a physician specializing in ER medicine. EMTs are involved in triage as are nurses. If you didn’t want to confine your work to triage and would consider something less acute, your options open even further. You could be a PA, Nurse Practitioner, CRNA, or any of the other allied health professional like optometrist, podiatrist or dentist. You might need to move your commission date of you do any of the post-secondary options.
There’s really no reason not to do what you want and you certainly aren’t too deep in your studies to change.
Just as an observation, postgraduate education should not impact commissioning date. The military has programs that allow new officers to immediately go into a relevant and needed graduate program. You can be commissioned, go to med school, and do a residency all while serving.