It sounds like you have had quite a disruption to your health recently! Hopefully you will be feeling back to normal soon. However, with such a sequence of events, from the fever, to the gastritis, to the joint problems, the best thing you can do to make sure you take care of your health is to see your primary care physician
to go over your symptoms and health history. It may be that you had some unfortunate luck and developed several illness
close together, but it is important to make sure that a physician does a thorough history, not only of your recent illnesses but of anything you might have had in the past, as well as a complete physical exam. There are some infections that can cause joint problems, and it is important to exclude this as a cause of your knee pain. Auto-immune conditions can also sometimes cause this constellation of unusual symptoms that develop in a previously healthy person. In this case, knowing a little more about your family history may be helpful. Finally, if you are still having pain in your knee, it is important that this be addressed. If you haven't seen your orthopedic surgeon
in follow-up, you need to do that to make sure that you don't need further evaluation or therapy. Good luck!