I am fearful to post here, as I don't want to catch what you have ;)
Honestly the best and only answer is a better Doctor. Doctor do more than many think, at least that is my opinion. I think doctors not only heal hurt players, but they also keep the team healthy. Whether that is ensuring good nutrition, helping players stretch or giving them "helpful" needles, doctors do help keep players healthy.
I would bet that in the top divisions most managers have either level 4 or 5 doctors at minimum. If I am going to spend the kind of money on players and a level 6 trainer, I have no issue spending a bit extra on a top tier doctor.
It is unfortunate to hear of your string of bad luck, but trust me a better doctor will help :)