Follow your dreams my man! Get higher education if you haven't already, take extra courses on mental health, addictions etc and get ahead of the rest of the candidates. You mentioned you had a few surgeries and medical history which depending on the extent of it might put you behind. But with a bunch more credentials under your belt and if you are still able to preform the job you will be just as competitive as the rest.
Great thing about healthcare is there are so many different sectors you can get into, you don't necessarily HAVE to be in the front line to start. In Canada at least you can start as a nurse for a few years then receive some extra training and move into paramedics and you will have a way higher chance of getting in.
Just don't give up bro